Page 163 - DMGT209_QUANTITATIVE_TECHNIQUES_II

Quantitative Techniques-II

Notes

Did u know? How to reduce non-sampling error?

1. For non-response – provide incentives such as a gift or cash. This enhances the
possibility as well as incidence of response.
2. Data error: Don’t ask question, which respondents cannot answer. Also, do not ask
sensitive questions.
3. Train the interviewer to establish a good rapport with the respondents.
4. Avoid leading questions.

5. Pre-test the questionnaire.
6. Modify the sampling frame to make it a representative of the population.

Self Assessment

Fill in the blanks:
11. A …………. is a specific list of population units, from which the sample for a study being
chosen.
12. ………….. occurs during the data collection, analysis of data or interpretation.

8.6 Sample Size Decision

1. The first factor that must be considered in estimating sample size, is the error permissible.
2. Greater the desired precision, larger will be the sample size.

3. Higher the confidence level in the estimate, the larger the sample must be. There is a
tradeoff between the degree of confidence and the degree of precision with a sample of
fixed size.
4. The greater the number of sub-groups of interest within the sample, the greater its size
must be.

5. Cost is a factor that determines the size of the sample.
6. The issue of response rate: The issue to be considered in deciding the necessary sample
size is the actual number of questionnaires that must be sent out. Calculation-wise, we
may send questionnaires to the required number of people, but we may not receive the
response.

Example: We may like to obtain the family income level from a mail survey, but the
researcher may not receive response from everyone. If the researcher feels the response rate is
40%, then he needs to despatch that many extra questionnaires. A low percentage of response
can cause serious problems to the researcher. This is known as the non-response error.
Non-response error may be due to 1) failure to locate, 2) flat refusal
The failure to locate: People move to new destinations. However, if the sample frames used are
of recent origin, this problem can be overcome.
Flat refusal: We do not know if those who did not respond hold different views or opinions
from those who responded.

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