concept analysis of similarity applied to nursing diagnoses: implications for educators

Concept Analysis of Similarity Applied to NursingDiagnoses: Implications for Educatorsijnt_1163 144..155

Sharie Falan, PhD, RN-BC, CPHIMS

PURPOSE. This philosophical inquiryexamined similarity using the conceptanalysis methodology by Walker andAvant (2005).DATA SOURCES. Data were obtained fromGoogle, CINAHL, PsychINFO, andPubMed using keywords “similarity,”“concept analysis,” and “similarityconcept analysis.”DATA SYNTHESIS. Various definitions, uses,and defining attributes of similarity wereidentified; model cases were presentedalong with antecedents, consequences,and empirical referents.CONCLUSIONS. The concept analysis ofsimilarity identified five definingattributes, antecedents, consequences, anddifferent ways to measure the concept.IMPLICATIONS FOR NURSING

PRACTICE. Representing nursing careinvolves similarity and when applied canpromote or enhance sharedunderstanding.Search terms: Concept analysis, nursingterminologies, similarity

Bronson School of Nursing, College of Health and HumanServices, Western Michigan University, Kalamazoo,Michigan.

Accuracy and consistency in the representation andcommunication of patient care are important becausein the United States over 98,000 deaths are caused bypreventable errors in healthcare delivery each year(Institute of Medicine, 1999). The Bush Administra-tion, also concerned about errors, issued ExecutiveOrder No. 13335 (2004), called for the ElectronicHealth Record (EHR), to improve the exchange ofpatient information, accuracy, and quality of patientcare. Nurses agree that accuracy and consistency isimportant through their support of meaningful use ofthe EHR and the use of nursing classifications tofacilitate data aggregation, evidence-based practice,and research (Alliance for Nursing Informatics, 2009;Levin, Lunney, & Krainovich-Miller, 2004). Accuracyand consistency in documentation of nursing con-cepts are important to patient safety because the iden-tification of nursing concepts drives nursing care.However, before a judgment of accuracy can be made,it is necessary to understand how nursing conceptsare selected in the delivery of patient care. The selec-tion of nursing concepts to represent care is a “simi-larity” issue that has had little exploration in nursing.Similarity facilitates the organization and categoriza-tion of information to nursing concepts and has thepotential to promote “shared understandings” in therepresentation and communication of patient prob-lems and care. To increase nursing’s knowledge ofsimilarity so it can be used in nursing practice, aconcept analysis was performed.

In nursing, a concept analysis is an endeavor togroup or categorize information, a concept, to clarify

This article is part two of a two-part series that describes theconcept of similarity as it relates to nursing practice.

International Journal ofNursing Terminologies and Classifications

© 2010, The AuthorInternational Journal of Nursing Terminologies andClassifications © 2010, NANDA Internationaldoi: 10.1111/j.1744-618X.2010.01163.x

144 International Journal of Nursing Terminologies and Classifications Volume 21, No. 4, October-December, 2010

its meaning. The purpose of a concept analysis is todescribe the concept well enough so that defining char-acteristics can be determined and used to distinguish“likeness or unlikeness” between concepts (Walker &Avant, 2005, p. 64). Lastly, a concept analysis clarifiesvague concepts and provides a means to commonunderstandings in nursing practice. Next, the method-ology for the concept analysis is explained.

Methodology

The concept of similarity is analyzed using theWalker and Avant (2005) methodology and begins witha brief discussion about how sources of similarityinformation were obtained, followed by a descriptionof the aims and perspectives of similarity from variousdomains. Then, defining attributes are identified fromthe literature, along with the presentation and discus-sion of relevant cases. The antecedents, consequences,and empirical referents are used to further clarify simi-larity, followed by nursing implications and a summa-tive conclusion.

Sources of Similarity Information

The process of understanding similarity included anInternet search of the terms “similarity,” “conceptanalysis,” and “similarity concept analysis” byusing Google, PsychInfo, CINAHL, MEDLINE, andPubMed. Similarity has its use in many domains suchas music, geometry, linguistics, business, research, andnursing, just to name a few. In a review of the litera-ture, one Formal Concept Analysis (FCA) was foundthat described a mathematical computational measureof text similarity (Tam, 2004). An in-depth discussionof the introduction of similarity into mathematicscurricula was also found (Lo, Cox, & Mingus, 2006).Because the only available concept analysis focused onmathematics computation and geometric shapes, aconcept analysis in nursing was warranted. The nextsection begins with a discussion of the aims of thisphilosophical inquiry.

Aims

The aims of this concept analysis were to clarify themeaning of similarity and identify multiple consider-ations for measuring the concept. In the practice ofhealth care, providers must be accurate in their inter-pretation of information. In order to be accurate,healthcare providers compare what they observe orsense to something pertinent, a standard, and makejudgments based on it. The process of similarity limitsthe amount of information that is considered whenmaking a judgment. Therefore, it is helpful to knowhow the standard is selected and what contributes toor affects the selection process. Although the use ofnursing terminologies and standards in the EHR aresupported by the Alliance for Nursing Informatics(2009), use of terminologies alone is insufficient. Inorder to have meaningful use of the terminologiesamong practitioners, consistency in selection of con-cepts is necessary because it allows for prediction andplanning of healthcare needs and resources (Ameri-can Nurses Association, 2010; Keenan, Falan, Heath, &Treder, 2003; Lunney, Delaney, Duffy, Moorhead, &Welton, 2005). Consistency can be accomplished byunderstanding similarity and how it is expressed byclinicians not only in the realm of nursing terminolo-gies but also throughout all phases of the nursingprocess. The important goal in nursing is to provide adependable approach to data collection and interpre-tation so that each member of the healthcare teamunderstands communication of care, patient out-comes, and the knowledge generated from it. Byunderstanding similarity, researchers, educators, andclinicians will have a solid grasp on factors that influ-ence nurses when they select certain nursing conceptsover others, how prior knowledge influences thoseselections, and they will be able to track and promotedesired consistency. These factors depend on similar-ity, and similarity is a step toward desired uniformity(Lin & Murphy, 2001; Marton, 2006; Medin, Gold-stone, & Gentner, 1993; Rosch & Lloyd, 1978; Smith,1989). Similarity has many applications in nursing,

International Journal of Nursing Terminologies and Classifications Volume 21, No. 4, October-December, 2010 145

but for this inquiry, the concept analysis of similarityis applied to the use of nursing terminologies, specifi-cally the nursing diagnoses (NANDA) taxonomy as away of demonstrating the concept. Similarity is themeans by which information is categorized into con-cepts that in turn can result in consistency, accuracy,and shared understanding.

Perspectives and Related Concepts

Similarity and Related Concepts

The first requirement of a concept analysis is toexamine existing definitions of the concept. The onlinedictionary definition of the noun similarity is (a)“equivalence,” (b) “resemblance,” and (c) correspond-ing “features” or “characteristics” (The AmericanHeritage Dictionary of the English Language, 2009c).Equivalence is defined as having the same “value,force, or significance” (The American Heritage Dictio-nary of the English Language, 2009a). Resemblance isdefined as having a “degree, kind, or point of like-ness” (The American Heritage Dictionary of theEnglish Language, 2009b). Using Roget’s II: The NewThesaurus (1995), synonyms of similarity are (a) “like-ness,” (b) “correspondence,” (c) “sameness,” and (d)“a quality or state of being alike.” Similarity is alsoconsidered a form of parallelism such as in analogieswhere objects and events are different but the rela-tionships between them are the same (WordNet,2009). As exemplified by the definitions, there are dif-ferent ways of defining similarity, but common amongthem is the implied comparison that occurs. The nextstep in a concept analysis is to explore similarity in theliterature.

Similarity in music. Similarity in music is definedas an act of comparison that results in an “average con-sensus” of agreement through comparing one song toanother (Logan, Ellis, & Berenzweig, 2003). Similarityapproaches are used in the music industry to classifymusic’s symbolic representations or features, such as

musical scores, melodious contours, the acousticalproperties, and cultural information. This means that acomparison occurs between an entity (e.g., musicalscore) and a standard (e.g., a different musical score)based on various features.

Similarity in geometry and mathematics. Geom-etry is primarily concerned with size, shape, and posi-tion of figures in space. Similarity in geometry refers toobjects that have the same shape. If two objects are ofthe same shape or have the same features but not nec-essarily the same size, they are considered similar(High Points Learning, 2009; Lo et al., 2006). Featuresare characteristics that are contained within the entityand standard that provide a means for comparisonsuch as the vertical and horizontal lines in the follow-ing two shapes: L (entity), L (standard). In thisexample, the purposeful act of comparing the featuresof an entity with the features of a standard is quiteeasy.

Similarity in linguistics. Linguistics explores theuse of words and their meanings. A similarity modelproposed by Weeds and Weir (2003) is used in linguis-tics to capture the usage patterns of nouns with verbs.In terms of words and their meanings, similarity isdefined as the appropriate use of one noun overanother (e.g., boaster versus bragger) and the associ-ated verb used in context. Similarity in this examplerefers to an emphasis on relationships that occurbetween words. The selection of words depends onwhat is intended to be communicated. There are certainconditions in which one word (e.g., bragger) is appro-priate to use, yet in other conditions a different word(e.g., boaster) becomes better. Words are concepts, andthey have inherent units of meaning. Selection of thebest word or words requires an intentional interactionwith not only the words themselves but also the char-acteristics of their meanings. Intentional interactionrefers to a deep understanding of how conceptsexist (in this case a “word” or “phrase” and clinicalevents) and how they are going to be used in context.

Concept Analysis of Similarity Applied to Nursing Diagnoses: Implications for Educators


To determine what characteristics are required tomake a prediction on which word should be usedto represent a concept, it requires an intentionalinteraction.

Similarity in research. The similarity concept isexplored in biological research. For example, similari-ties are found to occur in the hearing structuresbetween the Drosophila (fruit fly) and human beings(Cosetti et al., 2008). Commonalities in the hearingstructures are termed parallels (a form of similarity) inhearing. Parallelism refers to the common auditoryorgans, signaling, and cell functions that are necessaryto receive sounds occurring between the two species.These commonalities were found in sequence similarity,with respect to a matching succession of letters repre-senting DNA. The results of their study showed thatmutation of these genes resulted in hearing distur-bances across both species. Sequence similarity isimportant because it provides common meaning nec-essary for understanding hearing and how the hearingstructures work. This provides a necessary foundationfor further research to improve or limit geneticallyinduced hearing impairments. Although differentterms exist such as parallelism and sequence similarity,the underlying comparative structures are the featuresof the entities.

Similarity in relationships. Thematic similarity isdefined as “external or complementary relationsamong objects, events, people, and other entities thatco-occur . . .” (Lin & Murphy, 2001. p. 3). Thematicsimilarities can take on many forms. For example,there is a thematic similarity between a toothbrush andtoothpaste. While there are no matching features, the-matic similarities exist based on function. The tooth-brush holds toothpaste. Thematic similarities caninclude temporal relationships like the hospital billthat comes after service, or causal (e.g., water can causefluid overload) and spatial (e.g., a blanket lays on top ofa patient). When given a choice, more often than not,adults will choose a thematic approach to identifying

similarity rather than matching features or characteris-tics associated with entities (Lin & Murphy, 2001).

Similarity in business. Communication between asender and a receiver that results in shared meaning istermed similarity (Berthon, Pitt, & Campbell, 2009).Many organizations and businesses want to communi-cate simply and easily. Therefore, they use “brand” torepresent them in some way. Berthon et al. maintainedthat regardless of the clarity of communicationbetween an organization and stakeholders, the priorknowledge held by individuals or groups influence theinterpretation of “brand” and its meaning. In order tohave similarity in the meaning of the “brand,” priorknowledge of the stakeholders must be understood inorder to develop programs to ensure a commonmeaning across all employees.

Similarity in nursing. Similarity is used to deter-mine how nurses represent concepts (Falan, 2007,2010). Similarity was defined as the correspondencebetween objects, events, and/or circumstances basedon features (e.g., presence), dimensions (e.g., close-ness), and relationships (e.g., support, caring). InFalan’s (2010) study of medical surgical nurses, it washypothesized that different patterns and expressions infour levels of similarity would occur when nurses withan associate’s degree (ADN) or a baccalaureate degree(BSN) compared general and nursing image pairs.Levels of similarity ranged from the very basic surfaceform to the most complex form analogy.

• Surface is the comparison of characteristics like colorwithout regard to relationships (e.g., red car to redball).

• Literal is more extensive than surface, and it isthe correspondence of characteristics and relation-ships between two or more entities (e.g., patients,diseases).

• Thematic is less complex than analogy, and it is theunderstanding of relationships that occur betweenentities such as food and life. The thematic relation-


ship between the two is based on function such thatfood “functions to” sustain life.

• Analogy is the respect in which similarities occuracross dissimilar entities. For example, providingphysical support to someone in pain in somerespects is similar to providing psychologicalsupport for a person in emotional distress.

The results of the study showed that nurses describesimilarities from multiple perspectives (Falan, 2010).

The use of nursing terminologies in clinical settingshas been explored (Keenan et al., 2003; Maas, Johnson,Moorhead, Reed, & Sweeney, 2003; Moorhead,Johnson, Maas, & Reed, 2003). Although similarity wasnot defined explicitly in Keenan et al.’s work, compe-tency in the use of nursing terminologies was deter-mined by the selection of identical concepts, which isliteral similarity, by nurses with knowledge of thepatient. In this study, pairs of nurses evaluated a clinicalexemplar (an entity) and compared their observationsand findings with nursing concepts (standards). Inde-pendently, the nurses selected nursing concepts thatbest represented the clinical exemplar. Afterward, theselected concepts were compared among nurse pairs,and they were found to differ noticeably in part attrib-uted to differences in the familiarity with the patient.When differences occurred in the selection of concepts,nurses discussed what and why they determinedsomething as clinically important and how theyarrived at the final selection. Although differences infamiliarity of the patients might explain a portion ofthe differences, there is another perspective. Certainnurse pairs might have disagreed because the expert ofthe pair may have approached the exercise using athematic perspective, while the novice was onlycapable of utilizing a surface approach.

In summary, similarity has been extensively used inmultiple application domains including music, geom-etry, mathematics, business, biological research, andnursing. The next step in the concept analysis was toidentify attributes of the concept.

Defining Attributes

Through a review and synthesis of the literature,recurring characteristics of similarity conceptsemerged. Characteristics are qualities that separate oneconcept from other concepts, and they are called defin-ing attributes (Walker & Avant, 2005). In this research,a four-defining attributes tuplet is used to identifysimilarity.

Defining Attributes of Similarity

The definition of each attribute follows:

1. Entity is a single object, an event, a complex clinicalscenario, or an abstract idea learned and stored inmemory.

2. Standard is an arbitrary or authoritative referenceused to aid in the comparison process and unifycommunication among groups (e.g., normal bloodpressure range, or a NANDA concept such asExcess Fluid Volume; NANDA-International, 2009,p. 85).

3. Intentional interaction is the attainment of a deepunderstanding of an entity and of a standard (e.g.,understanding more about the patient than whatthey tell you, or understanding a terminologyconcept beyond name alone).

4. Comparison is the identification and evaluationof features or characteristics, qualities, quantities,and relationships between an entity and astandard.Once the above four defining attributes occur, asimilarity determination can be made.

5. Similarity determination is a conclusion aboutwhether an entity has some type of coherence withthe standard or does not.

Relevant Cases

Relevant cases provide an example of the concept aswell as those that are close yet different from the



concept. Four cases are presented in the following dis-cussion. Among these cases, the first is a model casethat exemplifies similarity.

Model Case

This case contains all of the defining attributes of theconcept. Attributes include an entity, standard, inten-tional interaction, comparison, and similarity determi-nation. Consider the following sentences as anexample of the model case:

(a) The 40-year-old man’s skin was blistered becauseof overexposure to the sun. Based on the severity ofthe burn, some blisters have already started tobreak open (entity).

(b) Impaired Skin Integrity (a standard, NANDA-International, 2009, p. 320)

Discussion. As it can be seen, the above modelcase involves all four defining attributes of similarity.Sentence (a) represents the entity and sentence (b)represents the standard. An intentional interactionwith the sentences occurs when they are read andunderstood for meaning. For sentence (a) the pres-ence of blisters means that the epidermis (skin) haschanged or been altered by the sun. The damage tothe skin resulted with an interruption in the skin’sintegrity. This means that the skin in the blisteredareas are more vulnerable to rupture and will haveincreased risk of infection. In sentence (b), themeaning of Impaired Skin Integrity is defined as“Altered epidermis and/or dermis” (NANDA-International, 2009, p. 320). But there is more in thephrase “Impaired Skin Integrity” than its definitionalone. There are defining characteristics that are com-pared with what exists in the entity or sentence (a).Next, the sentences are compared with each other formeaning. Based on what is read and understood, onecan conclude that sentences (a) and (b) have the samemeaning and characteristics, which is a similaritydetermination.

Borderline Case

A borderline case includes most of the definingattributes, but some may be missing, or there existssome differences in their expression (Walker & Avant,2005). The following is considered a borderlinecase:

Susan, a registered nurse, examined a patient (anentity) in the hospital who was admitted with conges-tive heart failure (CHF). She has cared for the patientfor 2 days and noticed that the patient’s legs weremore swollen than previously observed. The patientwas also having some dyspnea (shortness of breath),increased weight, chest edema, and clammy skin.Susan instructed the patient to elevate his legs and usehis incentive spirometer to help improve the depth ofbreathing. Finally, Susan determined that IneffectiveBreathing Pattern (NANDA-International, 2009, p. 138)was the most appropriate nursing problem at thistime.

Discussion. While the above nurse, Susan, inter-acted with a patient with CHF (an entity), it is unclearthat there was an intentional interaction (i.e., deeppurposeful understanding) with the patient and ifSusan was familiar with the standard. Susan identi-fied a change in the appearance of the patient’s legsand his breathing; however, there were more signifi-cant changes (i.e., edema in the chest, increasedweight, and clammy skin) that were not considered tocategorize the patient’s worsening status. Dyspnea isa characteristic of Ineffective Breathing Pattern, whichdoes not include the other symptoms. A more appro-priate concept to represent this scenario is DecreasedCardiac Output (NANDA-International, 2009). Thisconcept includes the essential characteristics identifi-able in this case and is defined as “Inadequateblood pumped by the heart to meet the metabolicdemands of the body” (NANDA-International, 2009,p. 139).

In sum, the nurse interacted with the patient butwithout sufficient understanding of either the patient


or the nursing concepts. As a result, there was limitedprecision in making the most appropriate meaningfulcomparisons between the patient and the nursingconcept that represents the problem. The lack of inten-tional interaction with the patient and the standardsimpinged on the fundamental comparisons. As aresult, the final similarity determination (i.e., matchingto standard) was incorrect and the nursing careactions required to complications of CHF were notsufficient.

Related Case

A related case is an illustration of the concept that isassociated with, but different from, the concept beingexamined because not all of the defining attributes arepresent (Walker & Avant, 2005). While it is near impos-sible to describe any object or concept without consid-ering some defining attributes of similarity, merenoticing may not lead to any similarity. Noticing isdefined as the act of becoming aware of something.Consider the following case:

A nurse went to a patient’s home to evaluate howbreast-feeding was going between the mother and herinfant. The nurse noticed that the living room was darkand subdued, a self-help book on depression was nextto the mother, and the room was in disarray—acommon phenomenon for new mothers. The nurseconcluded that the mother had difficulty breast-feeding her newborn based on the assessment. Thenurse identified that Ineffective Breastfeeding (NANDA-International, 2009) was the focus of care based oninformation collected by her direct observation.

Discussion. The nurse evaluated the patient andthe infant to determine a course of action. However,several things were noticed, but no action wastaken. Unlike similarity determination, the nursecompleted noticing, an act of becoming aware; never-theless, it does not involve intentional interactionand comparison that are necessary for similaritydetermination.

Contrary Case-Dissimilarity (Nonsimilarity)

Contrary cases are those instances that do notrepresent the concept under review. Dissimilarity isexampled by comparing the meaning of the followingtwo examples:

(d) Last week, a 46-year-old woman expressed sorrowat the loss of her daughter. The daughter recentlysuccumbed to cancer that had been affecting herlife for the last 3 years. The mother talked aboutseeking a support group to help manage the painof her loss. (entity)

(e) Ineffective Coping is defined as the “Inability toform a valid appraisal of the stressors, inadequatechoices of practiced responses, and/or inability touse available resources” (NANDA-International,2009, p. 254). (standard)

Discussion. The major concepts of sentence (d) areloss of a loved one, an end to a struggle, and a desire toseek societal assistance for coping with the loss. Sen-tence (e) suggests inadequate coping, which is charac-terized by “destructive behavior,” “inadequateproblem solving,” and “verbalization of the inability toask for help” (NANDA-International, 2009, p. 254).There are differences in subject matters and the rela-tionships. Therefore, the meaning of the entity andstandard are not the same.

To complete the concept analysis, three additionalfactors that influence similarity determinations areexamined. These are the antecedents, consequences,and empirical referents.

Antecedents

In order for a concept to occur, the antecedents (i.e.,what comes first) must be identified and cannot be thedefining attributes (Walker & Avant, 2005). The ante-cedents influence similarity determinations. For simi-larity, the antecedents are context, frame of reference, andprior knowledge and experience.



Context

Similarity is often described as “a quality or state ofbeing alike” (Roget’s II: The New Thesaurus, 1995). Tomake decisions about the likeness of entities, thecontext must be identified first. The context influenceswhich characteristics of an entity are considered mostimportant (Croft & Cruse, 2004; Tversky & Gati, 2004).In nursing, the context means deciding the focal pointof care. Consider the following case:

Bill, a 70-year-old patient in a nursing home wasreceiving extensive physical therapy after an occur-rence of lower extremity cellulitis. After Billreturned to his room from physical therapy, thenurse asked how he was feeling, and he respondedthat he was feeling good. The observant nurse sawthe tenseness in his face and some stiffness in hismovement (entity) which are inconsistent withfeeling “good” (an arbitrary standard). Then, thenurse asked Bill about his pain. His response wasthat he really hurt.

In this exemplar, the nurse must choose to focus onwhether the patient’s response “feeling good” or herown observation “facial tenseness and stiffness inmovement” is most salient. This pivotal point is anexample of selecting the context. The context is impor-tant and must be carefully considered because it pro-vides a background of making comparisons (Croft &Cruse, 2004; Tversky & Gati, 2004). Given the contextof facial tenseness and stiffness, the nursing conceptthat best represents the patient’s symptoms should beacute pain rather than impaired physical mobility(NANDA-International, 2009).

Frame of Reference

Since the context for making comparisons is quitebroad, a frame of reference narrows the context tofacilitate similarity comparisons. The definition of aframe of reference focuses on the specific conditions,

ideas, or assumptions on which the comparisons occur(Tversky & Gati, 2004). Using the above patientexample (i.e., Bill), a frame of reference would be the actof narrowing or determining the location and type ofpain. In this case, the source of pain was not fromcellulitis or acute pain from exercise. Rather, the painwas caused by a chronic condition called shingles. Theconcept that best fits this situation is chronic pain(NANDA-International, 2009). Without the frame ofreference, it is likely that an incorrect concept would beused to represent the pain.

Prior Knowledge (Education and/or Experience)

A determination of similarity infers that a judgmenthas been made (Cosetti et al., 2008; Falan, 2010;Keenan et al., 2003; Weeds & Weir, 2003; WordNet,2009). The antecedent to making a judgment is havingprior knowledge, which is defined as being familiar withsomething through education and/or experience. Priorknowledge helps focus attention on pertinent aspects ofan entity and the standard. For example, nurses usetheir prior knowledge to identify and to make sense ofsalient clinical features (Keenan et al., 2003). Thisknowledge helps nurses categorize their findings intothe best nursing concept. Prior knowledge influences ourexpectations in what is recognized and how it is inter-preted and remembered (Benner, 1984; Benner,Tanner, & Chesla, 1996; Chi, Feltovich, & Glaser, 1981;Proffitt, Coley, & Medin, 2000). For example, whenphysics students classified physics problems, novicespaid more attention to different criteria than expertsdid. Their differences reflected wide-ranging interpre-tations of the problems (Chi et al., 1981). Similarly, dif-ferences in the clinical knowledge of nurses have alsoled to varied responses by nurses (Benner, 1984; Falan,2010).

Consequences

Consequences are outcomes that result from aconcept. The major outcomes include organization and


categorization, knowledge development, and sharedunderstanding.

Organization and Categorization

The act of engaging in similarity determinationshelps separate concepts by providing a means toorganize and categorize information. In bioscience,sequence similarity performed on DNA strandsfrom two different species resulted in three commongenes (Cosetti et al., 2008). They learned that thesegenes behave in a like manner across species. Theinformation gained from this type of similarity facili-tates research that will benefit human beings. Inhealth care, nurses used similarity to match clinicalfindings to features contained in standardizednursing concepts (Keenan et al., 2003). These actionshelped nurses separate concepts and provided away of organizing and categorizing clinical infor-mation so appropriate care can be given andcommunicated.

Knowledge Development

A consequence to similarity determinations resultsin learning and knowledge development (Hayes &Taplin, 1995; Medin, Lynch, & Coley, 1997; Rips, 1989).Nurses demonstrated learning when they changedtheir concept selections after discussion with othernurses (Keenan et al., 2003). They became aware of dif-ferent ways of thinking about clinical events and thelinks to nursing concepts. Similarity determinationscan lead to learning and knowledge development ofclinical events and nursing concepts to provide bettercare for patients.

Shared Understanding

Similarity determinations can create a shared under-standing, which includes the mutual knowledge,beliefs, and assumptions among a group of people(Clark & Brennan, 1991; Falan, 2007, 2010; Mulder,

Swaak, & Kessels, 2002). Attaining a shared under-standing is exemplified by achieving coherence inconcept selection among nurses, reaching a commonmeaning for a “brand” in business, or arriving at an“average consensus” in music (Berthon et al., 2009;Keenan et al., 2003; Logan et al., 2003). In sum, theconsequences to similarity determinations includeorganization and categorization of information, learn-ing and knowledge development, and lastly sharedunderstanding.

The next step in a concept analysis is to determinethe empirical referents. Details follow.

Empirical Referents

Phenomena that demonstrate occurrence of theconcept can be measured and are called empirical ref-erents (Walker & Avant, 2005). The literature referencedby this inquiry shows multiple ways of describingsimilarity. This suggests that there are multiple ways ofmeasuring similarity.

In order to measure similarity, there must be anidentified entity, a standard, and an understanding ofeach. To conduct similarity determinations, there mustalso be meaningful understanding of the salient fea-tures between entities and standards for comparison.Tversky & Gati (2004) used a contrast model tomeasure the similarity of concepts, and it has beenwidely used in the research community. This modelidentifies the commonalities and distinctive features ofconcepts and calculates a measure for each, whichresults in a similarity measure that is the differencebetween the two. Similarity was also measured bymathematical algorithms such as those used in musiccategorization (Logan et al., 2003), the distributionmodel (Weeds & Weir, 2003), and the FCA for textsimilarity (Tam, 2004).

Similarity was measured in multiple ways innursing beginning with the matches between anentity and a standard (i.e., Image A, Image B) andword categories (i.e., medical personnel, healthcareproviders; Falan, 2010). Similarity was also captured



by exploring patterns and sequences of words used todescribe commonalities among images (i.e., health-care provider-giving-support, nurse-caring-sick-patient). Next, a similarity determination was alsorepresented by a rating scale between 1 (very dissimi-lar) and 10 (very similar) with four levels of wordchoices (from surface to analogy; Falan, 2010). More-over, identification of relationships between wordsand categories were used to explore similarity (Lin &Murphy, 2001).

In sum, from this concept analysis of similarity, themeaning of similarity is clarified as an intentionalinteraction with an entity and a standard such thatcharacteristics (i.e., features, values, quantities, quali-ties, patterns, and relationships) can be compared.Further, similarity determinations occur based on thecontext and frames of reference that are influenced byprior knowledge; each has important implications fornursing. As for measuring similarity, it is clear thatmultiple methods exist. The key point here is thatsimilarity can be as simple as matching some featuresor as deep as comparing how common relationshipsamong dissimilar concepts are applied in nursing.There are both qualitative and quantitativeapproaches for understanding and measuring similar-ity in the use of terminologies that create implicationsfor nursing.

Implications for Nursing

Application of similarity for concept analysis hasvast implications in nursing practice. Similarity canpromote accuracy in the organization and categoriza-tion of information to concepts. However, accuracycan hardly be achieved without a solid understandingof similarity. This is critical because it provides prin-ciples that nurse educators and nurses should considerwhen creating links between clinical events and theirrepresentation by nursing concepts. Some importantimplications for achieving accuracy through thesimilarity process, i.e., identifying the context andframe of reference, determining characteristics and

relationships, and utilizing prior knowledge, arebriefly summarized.

Identifying the Context and Frame of Reference

Context and frame of reference influence whatnurses attend to and interpret in clinical events. Thereare physical contexts and social relationships withothers that can influence meaning and interpretation ofevents (Croft & Cruse, 2004). In order to make similar-ity comparisons, a “common ground” must be identi-fied because it limits what information is considered inthe similarity determination. For nurse educators, itwill be helpful to explore the context and frame ofreference that nurses may use when selecting conceptsto represent clinical care. It is likely that differences inthese constraints will emerge among nurses andprovide opportunities for discussion and modificationin the way that key aspects of clinical events be judged.

Determining Characteristics and Relationships

Accuracy in the selection of concepts requiresidentification of characteristics, their relationships,and patterns. In nursing, clinical events consist ofcharacteristics, relationships, and patterns that can belinked to the same elements in nursing concepts. Dif-ferences in nurses’ attention will lead to varied results.For example, nurses who primarily focus on relation-ships or patterns are likely different in the selection ofconcepts and conclusions from those who primarilylook at characteristics (Falan, 2010; Lin & Murphy,2001). Therefore, it is vital to understand what theyfocus on and provide redirection when necessary toimprove similarity matches between the clinical eventsand concepts. To understand nurses’ focal orientation,educators must allow nurses to elaborate on the keyaspects of clinical events that learners deem mostimportant. Nurses who primarily select literal orsurface-level similarities should be encouraged tothink about deeper levels of similarity such as thematicor analogy levels.


Utilizing Prior Knowledge

Prior knowledge comes from education and experi-ence. When learning concepts, nurses need to articu-late “what” is important and “how” is it important tothe concept. Understanding the “what” and “how” hasbeen linked to prior knowledge and experiences, andinfluences how concepts are determined (Benner, 1984;Chi et al., 1981; Hayes, Taplin, Longstaff, 2002; Heit,1994, 1998). Similarity determination may capture dif-ferences in nurses’ focal point of interest and may beuseful in helping predict concept use in nursing. Oncecaptured, the knowledge gained may be used toenhance prediction in the selection of concepts and topromote knowledge development in less experiencednurses.

Conclusion

This inquiry explored similarity through a conceptanalysis methodology. Similarity was defined, caseexamples were given, antecedents and consequenceswere discussed, and empirical referents were identi-fied. Several important nursing implications were alsoaddressed, and many questions can be answeredthrough similarity. We do not know how nurses’ arbi-trary standard differs from the authoritative standardof the nursing classifications. Nor do we know hownurses determine relevant features. It is not knownwhether some features carry more weight than othersdo and if nurses agree. It has yet to be determined thatnurses can make accurate use of authoritative stan-dards in the EHR without knowing the definitions,characteristics, or qualities that differentiate them. Cur-rently, it is not known whether nurses have a propen-sity to think in a certain way, such as literally orthematically, and how thinking influences conceptselection and the representation of care in the contextof similarity. As educators, nurses, and researchersseek to understand how similarities and differencesoccur among health providers in healthcare domains,applying the concept of similarity to the strategy is

likely to provide new knowledge and improve accu-racy in care representations.

Acknowledgments. This author would like to thankBernard Han, PhD, Gail Keenan, PhD, RN, JoyceThompson, Dr P.H., RN, Mary Ann Stark, PhD, RN,and Mary Lagerwey, PhD, RN for their contributionsand critique of this manuscript.

Author contact: [email protected]

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concept analysis of similarity applied to nursing diagnoses: implications for educators

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