O'Reilly logo

Top Market Strategy by Elizabeth Rush Kruger

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

2.3 Sample Size

Experience teaches us that the responses of a large sample tend to balance out and better represent the population of all potential respondents, whereas the responses of a small sample (i.e., less than 30 respondents) tend to skew. Thus we can only analyze a subgroup of a sample if we expect at least 30 reponses. For example, when 150 unbiased respondents answer a question with 5 possible answers, we expect 30 responses for each response option.

We can predict the population's responses when we analyze at least 30 responses from a proportionally representative sample.

Table 5. Validity Errors

Types of errorDefinitionsExamples

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required