**Sample Size: How Many Survey Participants Do I Need?**

In order to have confidence that your survey results are representative, it is critically important that you have a large number of randomly-selected participants in each group you survey.

10 31.6

20 22.4

50 14.1

100 10

200 7.1

500 4.5

1000 3.2

2000 2.2

5000 1.4

10000 1

__Sample Size____Margin of Error__(%)10 31.6

20 22.4

50 14.1

100 10

200 7.1

500 4.5

1000 3.2

2000 2.2

5000 1.4

10000 1

You can quickly see from the table that results from a survey with only 10 random participants are not reliable. The margin of error in this case is roughly 32%. This means that if you found, for example, that 6 out of your 10 participants (60%) had a fear of heights, then the actual proportion of the population with a fear of heights could vary by ±32%. In other words, the actual proportion could be as low as 28% (60 - 32) and as high as 92% (60 + 32). With a range that large, your small survey isn't saying much.

If you increase the sample size to 100 people, your margin of error falls to 10%. Now if 60% of the participants reported a fear of heights, there would be a 95% probability that between 50 and 70% of the total population have a fear of heights. Now you're getting somewhere. If you want to narrow the margin of error to ±5%, you have to survey 500 randomly-selected participants. The bottom line is, you need to survey a

*lot*of people before you can start having any confidence in your results.