Download - Topics in Special Education Research
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Topics in Special Education
ResearchSession 4: Causal-comparative & Correlational
Research& Survey Methods
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Inter-observer agreement (IOA)- involves 2 observers measuring the same behaviors at the same time◦ It is most often used to determine the reliability of
observations of the DEPENDENT VARIABLE Treatment Integrity/Fidelity
(of treatment/intervention/ INDEPENDENT VARIABLE)◦ This is how the researcher measured how well the
treatment/intervention was implemented◦ Commonly done using checklists and other observers
recording the completion of these checklists
Difference between Inter-observer agreement & Treatment integrity/fidelity
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The main difference between experimental/quasi-experimental research designs AND other designs is…
They MANIPULATE the independent variable
Basically…..they introduce an intervention, while other methods (except for single-subject) do not systematically introduce an intervention
….seeks to make CAUSAL CONCLUSIONS
Experimental and Quasi-Experimental vs other designs
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A detailed explanation of the assignment is posted on the wiki
What should you be doing in your groups?◦ At this point you should have a topic and start
coming up with your framework for your research project (based on literature).
◦ Start to draft your conceptual framework, research questions & identify your dependent and independent variables
◦ You should walk away from your group time with a list of tasks to complete.
Proposal Assignment & Group Work
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1. Socially Important Issue:
2. Conceptual Model/Hypothesis:
3. Research Question(s):
4. Dependent Variable:
5. Dependent Variable Measure:
6. Independent Variable:
7. Independent Variable Measure:
8. Research Design:
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PSU Human Subjects Research Review Committee (HSRC)
http://www.rsp.pdx.edu/compliance_human.php
Portland State University (PSU) is responsible for the rights and welfare of human subjects involved in research sponsored or conducted by the university. In order to meet this responsibility, the University established the Human Subjects Research Review Committee.
Members are charged with reviewing all research conducted under the auspices of PSU that involves human subjects to ensure adequate protections are in place.
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Review for Quiz
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Steps in the Research/Scientific Process
1. Identify socially important issue
2. Review current literature
3. Define conceptual model
4. Define specific hypothesis(es) and research question(s)
5. Define dependent variable(s)/measure
6. Identify independent variable(s)/measures
7. Select appropriate research design
8. Obtain consents 9. Collect data 10. Analyze data 11. Communicate
results Written presentation Oral presentation
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Seeks to make causal conclusions.
Direct manipulation of an independent variable (intervention)
Difference between experimental design and quasi-experimental design is the use of random selection of participants and conditions.
Experimental Design
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Refers to whether a study is able to scientifically answer the questions it is intended to answer.
Extent to which your test (or study) measures what it intends to measure.
Validity
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Changes observed in the dependent variable (outcome) are due to the effect of the independent variable (intervention)…..
& not to some other unintended variables (extraneous, alternative explanations)
12 threats to internal validity (noted by Mertens, 2010)
E.g.., History, maturation, testing, instrumentation, mortality, etc.
Internal Validity
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External Validity= extent to which findings in one study can be applied to another situation.
AKA: ecological validity, generalizability
10 threats posed as questions (noted by Mertens, 2010)
E.g., detail/description of procedures, experimenter effects, sensitization, etc.
External Validity (think generalizability)
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Quiz
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Correct Quiz
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Steps in the Research/Scientific Process
1. Identify socially important issue
2. Review current literature
3. Define conceptual model
4. Define specific hypothesis(es) and research question(s)
5. Define dependent variable(s)/measure
6. Identify independent variable(s)/measures
7. Select appropriate research design
8. Obtain consents 9. Collect data 10. Analyze data 11. Communicate
results Written presentation Oral presentation
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Seeks to make causal conclusions.
Direct manipulation of an independent variable (intervention)
Difference between experimental design and quasi-experimental design is the use of random selection of participants and conditions.
Experimental Design
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Refers to whether a study is able to scientifically answer the questions it is intended to answer.
Extent to which your test (or study) measures what it intends to measure.
Validity
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Changes observed in the dependent variable (outcome) are due to the effect of the independent variable (intervention)…..
& not to some other unintended variables (extraneous, alternative explanations)
12 threats to internal validity (noted by Mertens, 2010)
E.g.., History, maturation, testing, instrumentation, mortality, etc.
Internal Validity
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External Validity= extent to which findings in one study can be applied to another situation.
AKA: ecological validity, generalizability
10 threats posed as questions (noted by Mertens, 2010)
E.g., detail/description of procedures, experimenter effects, sensitization, etc.
External Validity (think generalizability)
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Discussion
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Lecture
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Prepared by M. Hara ([email protected])
Statistics, statistics
Descriptive StatisticsWho is in your data?
sample population
Inferential StatisticsWhat your sample says about the population
sample
population
Mean, Median, Mode, standard deviation, variance Tests of significance
(t-, F-Tests)
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Central Tendency◦ Mean- average◦ Median- midpoint in distribution of scores◦ Mode- most frequent score
Variability◦ Range- total extension of the data (e.g., 1-10)◦ Standard Deviation- sum of deviations from the
mean squared. How well the mean summarizes the data.
◦ Variance- standard deviation squared. Used in sophisticated analyses
Descriptive Statistics
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Statistics, statistics
Inferential StatisticsWhat your sample says about the population
sample
population
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T tests- used when have two groups to compare. ◦ Independent samples t- if groups are independent
Different people in each group◦ Dependent samples t-: if two sets of scores are available for the same
people Matched groups
ANOVA (analysis of variance)- when you have more than 2 groups to compare OR more than one independent variable (reports an F-statistic, which is basically a t-value squared)
ANCOVA (analysis of covariance)- ANOVA that allows for control of the influence of an IV (e.g., characteristics of people) that may vary between your groups before treatment is introduced. ◦ Post-hoc method for matching groups on variables such as age, prior
education, SES, or a measure of performance
Inferential Statistics
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Tests of Significance Statistical analyses to determine whether a
difference is statistically significant (probability for result to occur by chance).
Yes or No answer
Alpha level (p=)◦ An established probability level which serves as the
criterion to determine whether to accept or reject the null hypothesis
◦ Common levels in education .01 .05 .10
Objectives 4.1 & 6.1
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Data
Addressing “WHAT” questions?
Depth of Information
Qualitative Data
Quantitative DataQuantitative Data
• Survey • Large Scale Assessments
Representative, Generalizability
Details, Depth, and Variability
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Numbers with Different Meanings
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Male
Female
(0)
(1)
Variable Type Example
• Gender
No
Yes
(0)
(1)
• Yes/No
Nominal
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Coding Data
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Check All that Apply
MS Word
MS Excel
Q. Which of the following applications have you used with your students? (Please check ALL that apply)
MS PowerPoint
SPSS
iMovie
iDVD
iTunes
iWeb
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Numbers with Different Meanings
30
Male
Female
(0)
(1)
Variable Type Example
• Gender
No
Yes
(0)
(1)
• Yes/No
• Likert-scale
StronglyDisagree
(1)Disagree
(2)Agree
(3)
StronglyAgree
(4)
Nominal
Ordinal
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Coding Data
31
Likert-scale
Q1. Overall, I have a good Parent-teacher Relationship.
DisagreeSomewhat Disagree
Somewhat Agree
AgreeStrongly Agree
Strongly Disagree
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Coding Data
32
Likert-scale
Q1. Overall, I have a good Parent-teacher Relationship. 1 2 3 4 5 6
NOTE: Distinguishable
Strongly Disagree
DisagreeSomewhat Disagree
Somewhat Agree
AgreeStrongly Agree
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Coding Data
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Multiple Categories
African American
Asian
Ethnicity
High School
Some College
Education Completed
BA/BS
Master’s
Doctoral
Caucasian
Hispanic
Other ____________
Decline to state
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Coding Data
34
Multiple Categories
African American
Asian
Ethnicity
High School
Some College
Education Completed
BA/BS
Master’s
Doctoral
Caucasian
Hispanic
Other ____________
Decline to state
1
2
1
2
3
4
5
3
4
5
888
NOTE: Mutually Exclusive, Exhaustive, and Distinguishable
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Numbers with Different Meanings
35
Male
Female
(0)
(1)
Variable Type Example
• Gender
No
Yes
(0)
(1)
• Yes/No
• Likert-scale
StronglyDisagree
(1)Disagree
(2)Agree
(3)
StronglyAgree
(4)
• Age, Annual Income, Test-score
Nominal
(Interval/Ratio)Scale
Ordinal
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Numbers with Different Meaning
36
Nominal
(Interval/Ratio)Scale
Male
Female
(0)
(1)
Variable Type Example
• Gender
No
Yes
(0)
(1)
• Yes/No
• Likert-scale
StronglyDisagree
(1)Disagree
(2)Agree
(3)
StronglyAgree
(4)
• Age, Annual Income, Test-score
Ca
teg
ori
ca
lN
um
eric
al/
Co
nti
nu
ou
s
Ordinal
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Numbers with Different Meaning
37
Nominal
(Interval/Ratio)Scale
Male
Female
(0)
(1)
Variable Type Example
• Gender
No
Yes
(0)
(1)
• Yes/No
• Likert-scale
StronglyDisagree
(1)Disagree
(2)Agree
(3)
StronglyAgree
(4)
• Age, Annual Income, Test-score
Ca
teg
ori
ca
lN
um
eric
al/
Co
nti
nu
ou
s
Who C
ARES??
Ordinal
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Numbers with Different Meaning
38
Nominal
(Interval/Ratio)Scale
Male
Female
(0)
(1)
Variable Type Example
• Gender
No
Yes
(0)
(1)
• Yes/No
• Likert-scale
StronglyDisagree
(1)Disagree
(2)Agree
(3)
StronglyAgree
(4)
• Age, Annual Income, Test-score
Ca
teg
ori
ca
lN
um
eric
al/
Co
nti
nu
ou
s
Why C
ARE??Ordinal
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Variable Types and Analysis
39
DependentVariable
IndependentVariable
Is therean association?
(a.k.a., Outcome) (a.k.a., Predictor)
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Variable Types and Analysis
40
DependentVariable
IndependentVariable
Is therean association?
(a.k.a., Outcome) (a.k.a., Predictor)
Where differences culminate
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Variable Types and Analysis
41
DependentVariable
IndependentVariable
Is therean association?
(a.k.a., Outcome) (a.k.a., Predictor, Intervention)
Where differences culminate
ContributingFactors
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Categorical
Numerical/Continuous
Categorical
Numerical/Continuous
Variable Types and Analysis
42
DependentVariable
IndependentVariable
Is therean association?
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Categorical
Numerical/Continuous
Categorical
Numerical/Continuous
Contingency Tables(a.k.a. Cross-tabs)
Variable Types and Analysis
43
DependentVariable
IndependentVariable
Chi-square testOr χ²-test
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Variable Types and Analysis
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DependentVariable
IndependentVariable
Categorical CategoricalContingency Tables(a.k.a. Cross-tabs)
GenderAnnual Salary
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Variable Types and Analysis
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DependentVariable
IndependentVariable
Categorical CategoricalContingency Tables(a.k.a. Cross-tabs)
Gender
Male Female
An
nu
al S
ala
ry
25K or below
26K - 35K
46K - 55K
36K - 45K
56K - 65K
66K and up
12% 4%
18% 6%
24% 11%
36% 39%
8% 28%
2% 12%
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Categorical
Numerical/Continuous
Categorical
Numerical/Continuous
Analysis of Variance
(a.k.a. ANOVA)
Variable Types and Analysis
46
DependentVariable
IndependentVariable
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Variable Types and Analysis
47
DependentVariable
IndependentVariable
CategoricalNumerical/Continuous
Analysis of Variance(a.k.a. ANOVA)
SAT9 Math Score
Males Females
t-test or F-test
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Categorical
Numerical/Continuous
Categorical
Numerical/Continuous
Regression
Variable Types and Analysis
48
DependentVariable
IndependentVariable
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Variable Types and Analysis
49
DependentVariable
IndependentVariable
Numerical/Continuous
Numerical/Continuous
Regression
SAT9 Math Score
Household Income
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Categorical
Numerical/Continuous
Categorical
Numerical/Continuous
Logistic Regression
Variable Types and Analysis
50
DependentVariable
IndependentVariable
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Variable Types and Analysis
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DependentVariable
IndependentVariable
Numerical/ContinuousCategorical
Logistic Regression
High school Exit Exam
SAT 9 Math
Fail
Pass
Probability of passing h.s. exam based on SAT-9 score
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Numbers with Different Meaning
52
Nominal
(Interval/Ratio)Scale
Male
Female
(0)
(1)
Variable Type Example
• Gender
No
Yes
(0)
(1)
• Yes/No
• Likert-scale
StronglyDisagree
(1)Disagree
(2)Agree
(3)
StronglyAgree
(4)
• Age, Annual Income, Test-score
Ca
teg
ori
ca
lN
um
eric
al/
Co
nti
nu
ou
s
Why C
ARE??Ordinal
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Categorical
Numerical/Continuous
Categorical
Numerical/Continuous
Contingency Tables(a.k.a. Cross-tabs)
Variable Types and Analysis
53
DependentVariable
IndependentVariable
Chi-square testOr χ²-test
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Categorical
Numerical/Continuous
Categorical
Numerical/Continuous
Analysis of Variance
(a.k.a. ANOVA)
Variable Types and Analysis
54
DependentVariable
IndependentVariable
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Categorical
Numerical/Continuous
Categorical
Numerical/Continuous
Regression
Variable Types and Analysis
55
DependentVariable
IndependentVariable
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Categorical
Numerical/Continuous
Categorical
Numerical/Continuous
Logistic Regression
Variable Types and Analysis
56
DependentVariable
IndependentVariable
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Statistics that function to describe the strength and direction of a relationship between two or more variables◦ Simple correlation coefficient (r=)
◦ Coefficient Determination- (r-squared). Amount of variance that is accounted for by the explanatory (independent or predictor) variable in the response variable (criterion variable).
◦ Multiple regression- to indicate the mount of variance that all of the predictor variables explain.
Correlational Statistics
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Way of quantifying the difference between two groups.
Not just was there an effect, but the magnitude of the effect.
Many ways to calculate
ES= [Mean of experimental group] – [Mean of control group]/Standard Deviation
R-squared, Cohens-D
Standard deviation is how well the mean summarizes the data
Effect Size
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Investigators attempt to determine the cause of differences that already exist between or among groups of individuals.
Describes conditions that already exist (a.k.a. ex post facto).
The group difference variable is either a variable that cannot be manipulated or one that might have been manipulated but for one reason or another, has not been.
Studies in medicine and sociology are causal-comparative in nature, as are studies of differences between men and women.
What is Causal Comparative Research?
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Similarities and Differences Between Causal-Comparative and
Correlational Research
• Similarities– Ex Post Facto research– Attempt to explain
phenomena of interest– Seek to identify variables
that are worthy of later exploration through experimental research
– Neither permits the manipulation of variables
– Attempt to explore causation
• Differences– Causal studies compare
two or more groups of subjects
– Causal studies involve at least one categorical variable
– Causal studies often compare averages or use tables instead of scatterplots and correlation coefficients
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Similarities and Differences Between Causal-Comparative and Experimental Research
• Similarities– Require at least one
categorical variable– Both compare group
performances to determine relationships
– Both compare separate groups of subjects
• Differences– In experimental research, the
independent variable is manipulated
– Causal studies are likely to provide much weaker evidence for causation
– In experimental studies, researchers can assign subjects to treatment groups
– The researcher has greater flexibility in formulating the structure of the design in experimental research
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Steps Involved in Causal-Comparative Research Problem Formulation
The first step is to identify and define the particular phenomena of interest and consider possible causes
Sample Selection of the sample of individuals to be studied by carefully
identifying the characteristics of select groups Instrumentation
There are no limits on the types of instruments that are used in Causal-comparative studies
Design The basic design involves selecting two or more groups that
differ on a particular variable of interest and comparing them on another variable(s) without manipulation
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The Basic Causal-Comparative Designs
Independent DependentGroup variable variable
(a) I C O(Group possesses (Measurement)
characteristic)
II –C O(Group does (Measurement)not possess
characteristic)
(b) I C1 O(Group possesses (Measurement)characteristic 1)
II C2 O(Group possesses (Measurement)characteristic 2)
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Examples of the Basic Causal-Comparative Design
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Threats to Internal Validity in Causal-Comparative Research Subject Characteristics
The possibility exists that the groups are not equivalent on one or more important variables
One way to control for an extraneous variable is to match subjects from the comparison groups on that variable
Creating or finding homogeneous subgroups would be another way to control for an extraneous variable
The third way to control for an extraneous variable is to use the technique of statistical matching
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Other Threats
• Loss of subjects• Location• Instrumentation• History• Maturation
• Data collector bias• Attitude
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Data Analysis In a Causal-Comparative Study, the first step is to
construct frequency charts & graphs.
Means and SD are usually calculated if the variables involved are quantitative.
The most commonly used inference test is a t-test for differences between means.
ANCOVAs are useful for these types of studies.
Results should always be interpreted with caution since they do not prove cause and effect.
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PSU uses a free web-based survey software called Qualtrics (available for student use)
http://oit.pdx.edu/node/908
Survey Methods
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Is there another way of collecting the information?
Is this method the most efficient and cost effective?
Will it provide you with the information you want in a valid manner?
Determine the purpose of your survey
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Have specific goals for the survey Consider alternatives to using a survey to
collect information. Select samples that well represent the
population studied. Use designs that balance costs with errors. Take great care in matching wording to
concepts being measured and the population being studied
Pretest questionnaires and procedures to identify problems prior to the survey
Best Practices
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Construct quality checks for each stage of the survey
Maximize cooperation or response rates within the limits of ethical treatment.
Carefully develop and fulfill pledges of confidentiality given to respondents.
Disclose all methods of the survey to permit evaluation and replication
Best practices continued
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Step 1- Determine PurposeStep 2- Identify a Sampling Plan & ModeStep 3- Design survey instrument Step 4- Test survey instrumentStep 5- Send out a letter of transmittalStep 6- Deliver the surveyStep 7- Analyze data from survey
Steps to designing, delivering, and analyzing surveys
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State specific objectives Consider the types of information needed Use your purpose to guide each of your other steps
and check back to this purpose often!◦ To make sure you are answering research questions
Simple descriptive- one-shot to describe moment in time
Cross-sectional- several groups at one point in time (e.g., 1st, 3rd, 5th grade students)
Longitudinal- cohort at different points (e.g., year 1, 2…after leaving school
Strengths and limitations of each??
Step 1- Determine Purpose of Survey
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Identify respondents (based on population you want to sample)◦ Think external validity…way you will generalize your results.
probability or nonprobability methods◦ Probability- each person has a probability of being surveyed.
random sampling, systematic sampling, and stratified sampling◦ Nonprobability methods
convenience sampling, judgment sampling, quota sampling, and snowball sampling
Based on what know about population decide how collect data:◦ Email, Web-based surveys, mail, telephone, personal
interviews, etc.
Step 2- Identify a Sampling Plan & Mode of data collection
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Random sampling- Each member of the population has an equal and known chance of being selected
Systematic sampling- called an Nth name selection technique
Stratified sampling- (1) Identify a subset of the population that share at least one common characteristic (males & females; managers & non-managers) and (2) their actual representation in the population, then (3) random sampling is used to select a sufficient number of subjects from each stratum.
Probability sampling
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Convenience sampling- selected because they are convenient. often used during preliminary research efforts to get a gross estimate of the
results, without incurring the cost or time required to select a random sample.
Judgment sampling- sample based on judgment. For example, draw the entire sample from one "representative" city, even though the population includes all cities. When using this method, the researcher must be confident that the chosen sample is truly representative of the entire population.
Quota sampling- like stratified sampling: (1) identify like characteristics and percentage of population, (2) convenience or judgment to select participants to represent characteristics and meet quota to represent population
Snowball sampling- Snowball sampling relies on referrals from initial subjects to generate additional subjects.
Non-probability sampling
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Review the literature There may be a survey that matches what you need (then use
and cite OR modify and cite) Determine question format
◦ Open-ended, close-ended, likert scale (0-5; never, sometimes, always) Avoid sensitive questions Be very clear Short items are better Avoid negative wording OR use positive wording Avoid asking about more than one idea…stay away from
AND…make another question to ask for additional information Avoid jargon/big words Emphasize …. (underline) critical words
Step 3- Design survey instrument
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Test instrument on yourself and others (not part of your sample!)
Pilot test to similar population. Use feedback to improve administration of
survey
Step 4- Test survey instrument
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Cover letter for mail surveys or as introductory letter/email for a phone, web, email, or personal interview survey.
Increases participation and limits incomplete surveys
Step 5- Send out a letter of transmittal
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Deliver the survey according to timeline Web-based or email surveys may have a
start date and date for completion by. Send follow up emails/letter/calls Monitor data as they come in to check for
errors----sooner than later. Send thank you emails/letters/calls
Step 6- Deliver the survey
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Follow up with non-respondents so you have some ideas why there was no response◦ You can then compare respondents vs non-
respondents Decide how to handle missing data Complete descriptive statistics: frequency,
percentages, mean, median, etc. Look for interesting patterns in the data Do sub-group analyses if possible Display data in tables & graphs
Step 7- Analyze the data
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Get together with your research group Based on your overall topic and possible
research questions...outline survey methods that you might give to participants or other stakeholders for the purpose of your research.
In-Class Application Activity