Question 1

What is a good sample size for a survey?

Accepted Answer

For most business surveys a sample of 384 people gives you a 95% confidence level with a 5% margin of error, whether your population is 10,000 or 10 million.

Question 2

How do I calculate sample size?

Accepted Answer

Use Cochran's formula: n equals Z squared times p times (1 minus p), all divided by e squared. For a known population, apply a finite population correction.

Question 3

What is the difference between confidence level and margin of error?

Accepted Answer

Confidence level tells you how often your result will land inside a given range if you repeated the study. Margin of error tells you how wide that range is.

Question 4

Do I need a bigger sample for a bigger population?

Accepted Answer

Not by much. Once your population passes about 20,000, the required sample size barely moves.

Question 5

What if my response rate is low?

Accepted Answer

Start with the sample size the calculator gives you and divide by your expected response rate.

Question 6

Common mistakes to avoid when choosing a sample size

Accepted Answer

Surveying whoever is easiest to reach, using a margin of error that is too generous, and ignoring non-response are the three most common mistakes.

Question 7

How do I calculate sample size when I have several segments?

Accepted Answer

Treat each segment as its own study. Calculate a sample size for each group and add them together.

Question 8

Does the type of study change the sample size I need?

Accepted Answer

Yes. Pricing studies and investment decisions need tighter margins, while quick pulse surveys can live with wider margins.

Question 9

When should I talk to a market research consultant?

Accepted Answer

A consultant is useful when the study is strategic, when you are weighting results across segments, or when the findings will drive investment.