Test
There are different ways to test for non-response bias. In e-mail surveys some values are already known from all potential participants (e.g. age, branch of the firm, ...) and can be compared to the values that prevail in the subgroup of those who answered. If there is no significant difference this is an indicator that there might be no non-response bias.
In e-mail surveys those who didn't answer can also systematically be phoned and a small number of survey questions can be asked. If their answers don't differ significantly from those who answered the survey, there might be no non-response bias. This technique is sometimes called non-response follow-up.
Generally speaking, the lower the response rate, the greater the likelihood of a non-response bias in play.
Read more about this topic: Non-response Bias
Famous quotes containing the word test:
“The test of an adventure is that when you’re in the middle of it, you say to yourself, “Oh, now I’ve got myself into an awful mess; I wish I were sitting quietly at home.” And the sign that something’s wrong with you is when you sit quietly at home wishing you were out having lots of adventure.”
—Thornton Wilder (1897–1975)
“It is commonly said ... that ridicule is the best test of truth; for that it will not stick where it is not just. I deny it. A truth learned in a certain light, and attacked in certain words, by men of wit and humour, may, and often doth, become ridiculous, at least so far, that the truth is only remembered and repeated for the sake of the ridicule.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)
“To answer a question so as to admit of no reply, is the test of a man.”
—Ralph Waldo Emerson (1803–1882)