guideline for report writing and error calculation

7/30/2019 Guideline for Report Writing and Error Calculation

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Appendix A

Guidelines for Technical Report Writing

A-1 General Remarks

In your formal studies of chemical engineering, you will be always required to submit

technical reports which effectively communicate the work which you have conducted.

Therefore, your reports should seek to inform, instruct, and often to persuade that its

interpretation of data is the correct one. Greatest clarity with the least number of words

becomes an essential constraint. In general, use shorter words rather than longer ones; avoidredundancy and verbosity, be consistent with the tenses, use past tense, passive voice, and third

person to describe what was done. Backup your judgments with data and scientific facts and

avoid sensationalism. Avoid unnecessary technical jargon; use simple expressions, and avoid

excessive speculation in discussing your results. Always proofread your report, and then read it

again.

Every table, graph, chart, drawing etc. must have a number and a title to identify it and must

be referenced in text body of the report. Figures, charts, and drawings usually have their

numbers and titles below whereas tables have their numbers and titles above.

Symbols, subscripts, abbreviations, superscripts and letters must be defined the first time they

occur in the text and listed in the Nomenclature section.

Plagiarism is not permitted, always give reference to the source of any piece of

information you copy from the literature. Cite your references as you proceed through the

report using embraced number (e.g., [1], [2]) and match a list of numbered references at the

end of your report. References must occur in (sequential) order in the body of your report.

A-2 Report Components and Organization


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Reports are to be printed on A4 plain white paper. The format of the report must be as

follows: double spaced using an appropriate font (Times, Ariel, etc) with 1.5 left, 1.0

top, bottom, and right margins. The font should be 12 pt for the report body, and may be 14

pt for the headings. Main headings should be bold and subheadings should be indented with

no bold. Page numbering is required in the bottom right of each page of the report body.

The Abstract and the Table of Contents must be numbered with i, ii, iii, etc , whereas the

report body, starting with the Introduction, must be numbered as 1, 2, 3, etc.

The report must be organized in the order listed below with each section beginning on a new

page.

1. Cover Page2. Abstract3. Table of Contents

a. List of Figures

b. List of Tables

4. Objectives5. Introduction/Literature Review6. Theoretical Background7. Experimental: Set-up and Procedure8. Results and Discussion9. Conclusions and Recommendations10.Nomenclature11.References12.Appendices

Below is a brief description of each section:


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1. Cover PageThe cover page should b e kept si mple . It should i nc lude the title of the experiment, the

name of the group members and their university numbers, the name of the instructor to

whom the report is submitted, and the date of report submission. Use a bold larger font size

for the experiment title, but keep it reasonable. Remember that page numbering does not

start with the cover page.

2. AbstractThe abstract is the shortest but most important part of the report. It is the basis for another

reader to decide whether or not your work is of relevance to him. In the space of one or two

paragraphs the reader should grasp the essentials of the report. Thus it should be short,

precise, and direct. It should convey the objective of the experiment, what was performed

or measured, and how it was accomplished, the most important results obtained and do the

results compare with the theory.

3. Table of ContentsList every division and heading in the report and give the number of the page on which it

starts to appear. It is essential that titles and subtitles match those occurring in the text.

Therefore, the best approach here is to cut the titles and headings from the body of the report

and paste them in the Table of Contents. The following is an example of listing divisions

and headings:

Theoretical Background...................................................................................... 10

Criteria for VLE.............................................................................. .......... 12

VLE of binary liquids in the presence of salt .................................. .......... 16

Experimental ...................................................................................................... 20

All figures and tables must appear in the List of Figures, and the List of Tables,

respectively.

4. Objectives


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Mention the objectives of the project.

5. Introduction and Literature ReviewThis section introduces to the unfamiliar reader the needed background so that he/she canfollow up and understand the conducted work. Previous similar or related works done by

others is also presented in this section. Reference to the applicability of the topic should also

be given. The objectives of the study are included at the end of the introduction. The

introduction is often less than a few pages long, if a Theoretical Background section is also

presented.

6. Theoretical BackgroundThe section presents the theoretical basis of the work and the related equations that will be

used in the analysis of the data. Complete derivation of the equations, if needed, is usually

included in the Appendices section.

7. Experimental MethodsThis section lists the chemicals used with their purity, presents a description of the

equipment (with the accuracy of each) with a schematic diagram, and explains the

experimental procedure, in step, followed in the experiment, and safety concerns.

8. Results and DiscussionIn this section, the results of your work should be presented in the clearest, most revealing

manner; statements, tables, and/or figures. Reference must be made to all figures and tables

given in the report. Whenever possible, give estimates of the precision of the data, and the

goodness of fit for any regressions which were performed. For some data reduction, further

statistical measures may also be informative. Tables and graphs must have titles and

numbers. The numbers should be in the order of their appearance in the report. Curves

should be drawn such that they show the best average representation of the data. If more than

one curve is plotted on the same graph, different symbols for data points can be used to

distinguish between them. Do not include a graph or a table and not say anything about it.


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Results must be discussed and compared with theory and/or literature. Each table or graph

should be explained in writing and the trends of curves must be justified. Sources of errors,

if any and their relation to the obtained data must be stated. Different paragraphs must be

used to discuss different tables or graphs. Always refer to figure number when discussing

the figures.

Sometimes two separate sections are used; one for results and the other for the

discussion. The thought here is that the results section should include only what was

measured and determined experimentally, and that the suggestion of models, speculation

about the cause of unexpected results, etc, should be placed in the discussion section.

Sample calculation (with steps and equations) must be shown.

9. Conclusions and RecommendationsIn this section, the conclusions or findings of the study should be presented. They must be

related to your discussion. Conclusions could be written either in the form of a bulleted list or

stated within paragraphs. For recommendation, present suggestions or ideas to modify the

procedure or the equipment in order to improve the experiment. Recommendations should be

relevant and justified by your observations and/or results.

10. NomenclatureYour report may include parameters, variables and constants, either in equations or just as a

reference. All of these must be defined in the nomenclature. A description and the units

of each entry must be given . This section usually contains a Roman, Greek,

Subscript/Superscript, and Abbreviation section. Each s e c t i o n must be arranged

alphabetically.

11. ReferencesAll the literature data used in the report must be referenced in the order of their

appearance in the report. A proper reference for a book should include the name of the

author(s), the title, the publishers, and place and year of publications (e.g., T. L. Brown,

H. E. LeMay Jr., and B. E. Bursten, Chemistry The Central Science. 9th

Edition, Prentice

Hall, (2003). For a journal article, the reference should include the name of the author(s),


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the article title, the journal title and volume number, the year in which this issue was

published and the page numbers on which the article begins (e.g., F. A. Abu Al-Rub, and

R. Datta, Separation of 2-Propanol-Water Mixture with Capillary Porous Plates,

Separation Science & Technology, Vol. 34, pp. 725-742 (1999).

12. AppendicesSupplemental material and additional information are placed in an appendix. Each

appendix must be referenced in the report. A separate page with the title of the appendix

(centered, both horizontally and vertically) is also usually placed before the information in

each respective appendix. The original data sheets used in the laboratory, with the title

and the date of the experiment, should also appear in this section. Instructors approval

must appear on that sheet.


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Appendix B

Experimental Errors and Data Analysis

References:

1. S. E. Kegley, and J. Andrews, The Chemistry of Water, University Science Books,

California, 1998.

2. J. R. Taylor, An Introduction to Error Analysis, 2n d

Ed., University Science Books,

Sausalito, 1997.3. R. B. Buckner, Surveying Measurements and their Analysis, 1983, Landmark

Enterprises

B-1 EXPERIMENTAL ERRORS

There is no perfectly accurate or exact experimental measurement. Many instrumental,

physical and human limitations can cause measurements to deviate from the "true" values of

the quantities being measured. These deviations are called "experimental uncertainties," butmore commonly the shorter word "error" is used. The true value of a measured quantity is the

value if all above mentioned limitations are eliminated.

Systematic (determinate) and random (statistical) errors are the two types of uncertainties in

any measurement.

Systematic error results from a bias in the instrument, and/or the experimental

procedure. Sources of systematic error include poor measurement technique, errors in

instrumental calibration. For example, if a refractometer we are using was calibrated

incorrectly and reads 2% higher than it should, then every refractive index reading we

record using this refractometer will have an error of +2%. Repeating the measurement

several times and taking the average of the readings will not reduce the size of this

systematic error. If the size and direction of the systematic error are known then it will be

possible to correct for it and thus eliminate its effects completely. Although it is not always


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possible to know the size and direction of the systematic error, the size of the error, or the

instrument accuracy, is usually provided by the instrument's manufacturer. Possible sources

of systematic error must be considered in each stage or phase of the experiment.

Random error occurs as a result of the statistical nature of things. Repeating a

measurement several times can help minimize this type of error. The reproducibility of

measurements made by identical methods determines the Precision or uncertainty of the

measurement. Precision or uncertainty can be expressed by the number of significant

figures (SF) used to express a measurement or a result. The more SF, the more accurate the

result is. The number of SF in any measured quantity is determined by the precision of the

measuring instrument, for example, if a balance measures the mass to two digits of grams,

the reported mass should be expressed with two digits of grams, e.g., 5.01 g. The following

rules should be considered when reporting data.

1. Always report data to the proper number of significant figures. In reporting data from your lab, thefollowing rules may be used

a. Pipette, volumetric flask and burette: two digits of ml.b. Balances: usually 4 digits of g.

2. Zeros:i. Leading zeros are not significant, e.g., 0.001 has one SF

ii. Captive zeros are significant, e.g., 1.003 has 4 SFiii. Trailing zeros are significant only if the number has a decimal point, e.g., 1.000 10 4 has 4 SF.

3. Addition and subtraction: In addition and subtraction, the answer has the same number ofsignificant figures as the least precise measurement, e.g.

4.03 g + 5.0023 g = 9.0323 g = 9.03 g

(Calculation) (Report)

4. Multiplication and division: When numbers are multiplied or divided, the answershould have the same number of SF as that of the least significant figures: e.g. 2.008

g 1.0 g = 2.008 g = 2.0 g

(Calculation) (Report)


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5. The number of SF in the number of trials is infinity.

6. When a series of calculations are performed, do not round off until the final result isobtained. When rounding off numbers:

i. If the insignificant figure is less than halfway, round down, e.g. 23.44 23.4ii. If the insignificant figure is more than halfway, round up, e.g. 23.46 23.5

iii. If the insignificant figure is exactly halfway, round to the nearest even digit, 23.45 23.4

Analysis of Random Error

1. Standard Error, , is the error in a single measurement. For a set of data composed ofnpoints (measurements), can be calculated by the equation:

1

)(1

2

n

xxn

i

i

(B-1)

Where x is the mean or average of the reading, and can be calculated using the equation

n

x

x

n

i

i 1 (B-2)

2. The relative standard deviation, RSD:RSD=( /x ) 100% (B-3)

The mean represents a value around which the data set is tending to center. The standard

deviation provides a measure of spread of the data around the mean. The relative standard

deviation is another way of representing the standard deviation as a percentage of the average

value. For a large data set, it is known that the observations (data values) will be distributed

normally around the average value with 68% of the observations are confined within

1x and 95% are confined within 2x . Therefore, a (questionable) data point lying


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outside the range 2x can be considered as an erroneous point and can be rejected away.

Note that the questionable data point(s) must be included in calculating x and .

Example:

Given the following measurements of the refractive index of a pure component,

calculate, the mean, the standard deviation, the relative standard deviation and decide

whether or not there are erroneous data points (that do not belong to the data set).

Sample number 1 2 3 4 5 6

Refractive index 1.4567 1.4566 1.4562 1.4569 1.4566 1.4564

4566.16/7394.81

n

x

x

n

i

i

0002.01

)(1

2

n

xxn

i

i

This means that our data is uncertain in the ten thousandth decimal place. 2x in this case

becomes: 1.4566 2(0.0002) = 1.4566 0.0004, i.e., any point outside the range (1.4562

to 1.4570) can be thrown away. Therefore, all points can be accepted. RSD = 0.01663%,

i.e., the reliability of these numbers is 0.01663%.

Propagation of Error in an Equation

When checking an equation using measured values the effects of all measurement errors

must be considered:

1. Additive Formulae: When the result R is calculated from two measured values: x withan error ofx, and y with an error ofy, and two constants a and b from the formulaR


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= ax by , then the error in the resultR is given by

22 )()( ybxaR

2. Multiplicative Formulae: IfR = a x y orR = a x / y, where a is a constant, then22

y

y

x

x

R

R

3. Powers: IfR = xn, thenx

x

nR

R


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guideline for report writing and error calculation

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