Data transformationThe process of changing data from original form to a

form that is more suitable to perform data analysis.Data conversionChanging the original form of the data to a new

formatMore appropriate data analysisNew variables

Data conversionThe process of changing data from original form to a

form that is more suitable to perform data analysis.Researchers modify the values. From date of birth

calculate the age. Subtract the birth year from the current year. Call it data conversion

Reducing the categoriesCollapsing or combining categories of a variable.Strongly agree + Agree = 1Undecided = 2Disagree + Strongly= 3

disagreeReducing from 5 categories to 3 categories

Creating New VariablesCreating new variable by re-specifying the data numeric or logical transformation e.g. Summative score = var1 + var2 + var3

TransformationMeasurement of social phenomenon. Some can be

measured directly (family income)Some others require the use of surrogates or proxies

(job satisfaction).Also draw upon others’ measures, already developed.

Modify according to need.

Indexes and ScalesIndexes and scales often used interchangeably.Scale is a measure to capture the intensity, direction, level,

or potency of a variable. Arranges responses on a continuum. A scale can use single indicator or multiple indicators. Ordinal level.

Index is a measure in which researcher adds or combines several distinct indicators of a construct into a single score. Composite score.

Scales and indexes combinedCombine the features of scales and indexes in a single

measure.Several indicators that are scales.Add these indicators to yield a single score.

Uni-dimensionalityAll items in a scale or index fit together i.e. measure a

single construct.Combine several specific pieces of information into a single

score or measure.All pieces measure the same construct (each sub-dimension

is part of the construct’s overall content)

ExamplesFeminist ideology: ideology about gender. It is an abstract

and general construct.Includes specific beliefs and attitudes towards social,

economic, political, family, sexual relations. All 5 areas are part of single general construct.

Parts are dimensions. Parts mutually reinforcing and together form a system of beliefs about dignity, strengths and power of women.

Index ConstructionIndex is combination of items into a single numerical score.

Various components or subgroups of a construct are each measured, then combined into one measure.

Example of consumer price index (CPI):CPI is created by totaling the cost of buying a list of goods

and services (food, rent, utilities).Compare this cost with previous year. May indicate

inflation.

Many types of indexesExam with 25 MCQ. Total number of correct answers

is a kind of index – a composite measure in which each question measures a small piece of knowledge.

All questions scored correct or incorrect are totaled to produce a single measure.

Occupational rating indexAnswer ‘yes’ or ‘no’ to the seven questions that follow on the characteristics of an occupation (truck driver, medical doctor, accountant, telephone operator). Score 1 for yes and 0 for no.

1. Does it pay good salary? 2. Is the job secure from layoffs or unemployment? 3. Is thee work interesting and challenging? 4. Are its working conditions (e.g. hours, safety, utilities) good? 5. Are there opportunities for career advancement and promotion? 6. Is it prestigious or looked up-to by others? 7. Does it permit self-direction and the freedom to make decisions? The seven questions are our operational definition of the construct good occupation

Rating indexTotal the 7 answers for each of the four occupations.Which occupation had the highest and the lowest

score? Measure the parts of a construct with multiple

indicators.

Face Validity of itemsEvery item in the index should have face validity.Each part of the construct should be measured with at

least one indicator.Better to measure the parts of a construct with

multiple indicators.

Example of college quality index

Dimension of quality college:Fewer students per faculty member,A highly educated faculty,More books in library,Fewer students dropping out of college,More students go to advanced degrees,Faculty members publish research papers.Score 100 college on each item, then ad the score for each to create an index score of college quality

Combine the score index for a dimension

Add a sub-index on teaching quality. The index contain 8 elements:

Average size of classes;Percentage of class time devoted to discussionNumber of different classes a teacher teaches;Availability of faculty to students outside class;Currency amount of readings assigned;Degree to which the faculty get to know each student;Student ratings of instruction.

College quality indexSimilar sub-index measures can be created for other

parts of college quality index.Combine all into a more global measure of college

quality.Measures the definition of a construct “quality of

college”

Weighting – important issueWhether or not to weight each item.Unless otherwise stated, assume that an index is un-

weighted.Un-weighted index gives equal weight to each item.Add up the items without modification

Scoring Remember the measurement of job satisfaction.

(dimensions and elements).Number of statements on each element.Likert scale (5) response categories: Strongly agree, agree,

neutral, disagree, s. disagree.There are positive and negative statements.For positive statements, score S. agree = 5, agree = 4,

neutral = 3, disagree = 2, s. disagree = 1.For negative statements reverse the scoring.

No. Statements S. Agree

Agree Undecided Disagree S. Disagree

1 I have a good opportunity for advancement in my job

√

2 I feel very comfortable with my co-workers

√

3 My pay is adequate to meet my necessary expenses

√

4 My work gives me a sense of accomplishment

√

5 My boss is impolite and cold √

6 My job is a dead-end job √

7 The company of my co-workers is boring

√

8 Pay at my level is less as compared to other organizations

√

No. Statements S. Agree Agree Undecided Disagree S. Disagree

1 I have a good opportunity for advancement in my job

√

5

2 I feel very comfortable with my co-workers

√

5

3 My pay is adequate to meet my necessary expenses

√

4

4 My work gives me a sense of accomplishment

√

2

5 My boss is impolite and cold √

3

6 My job is a dead-end job √ 5

7 The company of my co-workers is boring

√

5

8 Pay at my level is less as compared to other organizations

√

2

Score Index

There were 23 statements for different elements.On each statement a person could get a score of 1 to 5. Total score for a person could range from a minimum of

(23 X 1=) 23 to a maximum of (23 X 5 =) 115.Lower score indicating low job satisfaction and high score

as high job satisfaction

Use of score indexDifferent variables can have different score indexes. Use raw score indexes and apply appropriate statistics for

testing the hypothesis.Can also divide score index into different categories like

high job satisfaction and low job satisfaction.Cross-classify with some other variable, apply appropriate

statistics and test the hypothesis.