Sign Test

Question 1

Sign test

Answer 1

determines whether the number of positive and negative values in a sample is likely to be due to chance

Question 2

How do you evaluate the distribution’s tail?

Answer 2

compare alpha to the probability of obtaining any value as extreme or more extreme than the one obtained in the data
- use binomial distribution table to find likelihoods of the value obtained and more extreme (for two tailed evaluation, both tails of the distribution are added)
- compare p-value to alpha value α

Question 3

One-tailed evaluation

Answer 3

for a directional hypothesis, only one tail of the distribution is evaluated

Question 4

Two-tailed evaluation

Answer 4

for a non-directional hypothesis, both tails of the distribution are evaluated

Question 5

Sign test step 1

Answer 5

ensure that conditions are met for using binomial distribution

Question 6

Sign test step 2

Answer 6

formulate clear, specific null and alternate hypotheses

Question 7

Sign test step 3

Answer 7

set alpha value

Question 8

Sign test step 4

Answer 8

gather data and calculate number of pluses and minuses obtained

Question 9

Sign test step 5

Answer 9

determine the probability of getting an outcome this extreme or any more extreme
- extreme: favors alternate hypothesis
- non-directional H1: do two-tailed evaluation
- directional H1: do a one-tailed evaluation

Question 10

Sign test step 6

Answer 10

If the probability calculated in Step 5 is:
≤ α, reject H0 and accept H1
> α, retain (or “fail to reject”) H0

Question 11

Sign test step 7

Answer 11

Write out a clear, specific conclusion that is consistent with the wording of your original hypotheses

eg, “Reject H0 and conclude that a romantic partner’s scent affects sleep efficiency.”