How many responses do I need?
Most of our clients use Qualtrics with the goal of making inference to a certain population.
Sometimes it is finding out what America thinks of President Obama and other times it is gauging the interest of a new product among general consumers. Regardless of the question we are trying to answer, getting the correct sample is vital justifying the conclusions. We need to start with the right population.
If you are interested in students’ thoughts on buying textbooks online for example, the population of interest is students and not all adults. Once you have the right population you need to make sure you have enough respondents to validate your findings. Here is a simple table. Population represents the number of people in your population of interest.
Sample Size is how many respondents you need to make good inference to that population.
Population — Sample Size
100 — 80
500 — 217
1,000 — 285
5,000 — 357
10,000 — 370
50,000 — 381
1,000,000 — 384
Keep in mind that response rates for internet surveys can range from 10% to 50% so plan accordingly as you choose your panel.