Page 105 - DMGT209_QUANTITATIVE_TECHNIQUES_II

Quantitative Techniques-II

Notes 2. Assuming that a training programme is conducted for salesmen, the company wants
to measure the impact of its sales programme. If the company finds that the sales
have improved, it may not be due to its training programme. It may be because
their salesmen have gained more experience now and know the customer better.
Better understanding between salesmen and customer may be the reason for increased
sales.
Maturation effect is not just limited to test unit, composed of people alone. Organisations
also change, dealers grow, become more successful, diversify, and so on.
 Testing: Pre-testing effect occurs, when the same respondents are measured more than
once. Responses given at a later stage will have a direct bearing on the responses given
during an earlier measurement.

Example: Consider a respondent, who is given an initial questionnaire, intended to
measure brand awareness. After examining him, if a second questionnaire similar to the initial
questionnaire is given to the respondent, he will respond quite differently, because of the
respondent’s familiarity with the earlier questionnaire.

Pretest suffers from limitations of internal validity. This can be understood through an
example. Assume that a respondent’s opinion is measured before and after exposure to a
TV commercial of Hyundai car with Shahrukh Khan as brand ambassador. When the
respondent replies for second time, he may remember, how he rated Hyundai during the
first measurement. He may give the same rating to simply prove that he is consistent. In
that case, the difference between the two measurements will reveal nothing about the real
impact.
Alternately, some of the respondents might give a different rating during the second
measurement. This may not be due to the fact that the respondent has changed his opinion
about Hyundai and the brand ambassador. He has given different rating because he does
not want to be identified as a person with no change of opinion to the said commercial.

In both cases above, the internal validity suffers.
 Instrument Variation: Instrument variation effect is a threat to internal validity when
human respondents are involved.

Example: An equipment such as vacuum cleaner is left behind for the customer’s use for
two weeks. After two weeks, respondents were given a questionnaire to answer. The reply may
be quite different from what was before the trial of the product.
This may be because of two reasons:
(1) Some of the questions have been changed.
(2) The interviewers for pre-testing and post-testing periods are different.

The measurement in experiments will depend upon the instrument used for measurement.
Also, results may vary due to the application of instruments, where there are several
interviewers. Thus, it is very difficult to ensure that all the interviewers will ask the same
questions with the same tone and develop the same rapport. There may be difference in
response, because each interviewer conducts the interview differently.
 Bias in Selection: Bias in selection occurs because two groups selected for experiment may
not be identical. If the two groups are asked various questions, they will respond differently.
If multiple groups participate this error recurs frequently. There are two promotional
advertisements, A and B, for ‘ready to eat food’. The idea is to gauge the effectiveness of

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