When is a Sample Size too Small?

The issue of small number of respondents becomes apparent when combining low incidence and small target samples. Low incidence and/or small sample sizes may result in limited data for analysis. A minimum sample size of 40 is considered stable and usable information.

"Without an adequate number of respondents, the ability to break down the data and make meaningful conclusions is compromised".

Samples of low-incidence populations are a cause for concern. It is important to understand what approaches are available to deal with this issue.

The following are key recommendations and insights when working with small samples:

  1. Be cautious when conducting analysis on a small group of respondents.
  2. A small number of respondents does not allow you to make sound decisions or conduct detailed analysis.
  3. When you have only a few respondents it is possible to make some conclusions (e.g. the group is less likely to occur in the population).

 Estimated Number of Respondents Based on Sample Size and Reach

Target Sample Readership Reach
5% 15% 25% 40% 50%
225  11  34  56  90  113
400  20  60  100 160  200
500  25  75  125  200  250
800  40  120  200  320  400
1000  50  150  250  400  500
1150  58  173  288  460  575
1700  85  255  425  680  850
2000  100  300  500  800  1000

 

For more information on sample size and related topics read [ Sample Size Booklet. ]

 

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