Page 280 - DMGT404 RESEARCH_METHODOLOGY

Research Methodology

Notes Sign-test

Sign-test is used with matched pairs. The test is used to identify the pairs and decide whether the
pair has more or less similar characteristics.

Example: Suppose, an experiment on the effect of brand name on quality perceptions is to be
conducted. 10 persons are selected and asked to taste and compare the two products (beverage).
One of them is identified as branded well known beverage, and the other is a new beverage. In
reality, the samples are identical. The respondents who tested were asked to rate the two samples
on an ordinal scale. Two hypotheses are set up as follows:
H - there is no difference between the perceived qualities of two beverages.
0
H - there is a difference in the perceived qualities of two beverages.
A
12.6.2 Two Sample Tests

The following are the main examples of two sample non-parametric tests:

Mann Whitney “U” Test
(Rank Sum test)
This test is used to determine whether two independent samples have been drawn from the
same population. Suppose an experiment has obtained two sets of samples from two populations
and the study wishes to examine whether the two populations are identical.

Example: A computer company XYZ would like to choose the performance of
programmers, working in 2 branches, located in different cities. The performance indices of
employees:
Branch A Branch B
84 76
68 77
78 64
49 62
45 53

To find out whether there is any difference in the performance indices of employees of the two
branches.

Kolmogorov-Smirnov Test

This is used for examining the efficacy of fit between observed samples and expected frequency
distribution of data when the variable is in the ordinal scale.

Example: A manufacturer of cosmetics wants to test four different shades of the liquid
foundation compound – very light, light, medium and dark. The company has hired a market
research agency to determine whether any distinct preference exists towards either extreme. If
so, the company will manufacture only the preferred shade, otherwise, the company is planning
to market all shades. Suppose, out of a sample of hundred, 50 preferred “very light shade” 30
liked light shade, 15 the medium shade, and 50 dark shades. Do you think the results show any
kind of preference?
Since the shade represents ordering (rank), this test can be used to find the preference.

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