Sampling Design Measurement Scaling Dr Kishor Bhanushali sampling

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 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