Sampling Design & Measurement Scaling Dr. Kishor Bhanushali

sampling CENSUS AND SAMPLE SURVEY IMPLICATIONS OF A SAMPLE DESIGN

STEPS IN SAMPLE DESIGN Type of universe Sampling unit Source list Size of sample Parameters of interest Budgetary constraint Sampling procedure

Systematic Bias 1. Inappropriate sampling frame 2. Defective measuring device 3. Non-respondents 4. Indeterminacy principle 5. Natural bias in the reporting of data

CHARACTERISTICS OF A GOOD SAMPLE DESIGN (a) Sample design must result in a truly representative sample. (b) Sample design must be such which results in a small sampling error. (c) Sample design must be viable in the context of funds available for the research study. (d) Sample design must be such so that systematic bias can be controlled in a better way. (e) Sample should be such that the results of the sample study can be applied, in general, for the universe with a reasonable level of confidence.

Non-probability sampling and probability Sampling from finite population and infinite population purposive sampling Judgement sampling Quota sampling Simple random sampling Systematic sampling Stratified sampling Cluster sampling Area sampling Multi-stage sampling Sampling with probability proportional to size Sequential sampling

MEASUREMENT Measurement is a relatively complex and demanding task, specially so when it concerns qualitative or abstract phenomena By measurement we mean the process of assigning numbers to objects or observations properties like weight, height, etc., can be measured directly with some standard unit of measurement, but it is not that easy to measure properties like motivation to succeed, ability to stand stress and the like Technically speaking, measurement is a process of mapping aspects of a domain onto other aspects of a range according to some rule of correspondence

MEASUREMENT SCALES Nominal scale :simply a system of assigning number symbols to events in order to label them. - basketball players Ordinal scale : places events in order - student’s rank Interval scale : intervals are adjusted in terms of some rule, lack of a true zero - Fahrenheit scale Ratio scale : absolute or true zero of measurement-height, weight, marks

Sources of Error in Measurement Respondent : reluctant to express strong negative feeling, fatigue, boredom, anxiety, Situation: distortions Measurer: behaviour, style and looks Instrument :defective measuring instrument, complex words

Tests of Sound Measurement Validity ,Reliability, Practicality Validity refers to the extent to which a test measures what we actually wish to measure : (i) Content validity, (ii) Criterion-related validity, (iii) Construct validity Reliability has to do with the accuracy and precision of a measurement procedure : For instance, a scale that consistently overweighs objects by five kgs., is a reliable scale, but it does not give a valid measure of weight Practicality is concerned with a wide range of factors of economy, convenience, and interpretability

TECHNIQUE OF DEVELOPING MEASUREMENT TOOLS (a) Concept development; (b) Specification of concept dimensions; (c) Selection of indicators; and (d) Formation of index.

Scaling measurement problem in measuring attitudes and opinions procedures for attempting to determine quantitative measures of subjective abstract concepts Scaling describes the procedures of assigning numbers to various degrees of opinion, attitude and other concepts (i) making a judgement about some characteristic of an individual and then placing him directly on a scale that has been defined in terms of that characteristic and (ii) constructing questionnaires in such a way that the score of individual’s responses assigns him a place on a scale

Scale Classification Bases (a) subject orientation; characteristics of the respondent (b) response form; categorical and comparative (c) degree of subjectivity; subjective personal preferences or simply make non-preference judgement (d) scale properties; nominal, ordinal, interval and ratio scales (e) number of dimensions : ‘unidimensional’ and ‘multidimensional’ scales (f) scale construction techniques

The graphic rating scale The itemized rating scale

Method of paired comparisons Method of rank order Under this method of comparative scaling, the respondents are asked to rank their choices

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