Identify whether the studies described here are based on (1) single samples, (2) paired samples, or (3) independent samples.

; ;Identify whether the studies described here are based on (1) single samples, (2) paired samples, or (3) independent samples.

a. ; ; ; ; ; ;An investigator compares vaccination histories in 30 autistic schoolchildren to a simple random sample of non-autistic children from the same school district.

b. ; ; ; ; ; ;Cardiovascular disease risk factors are compared in husbands and wives.

c. ; ; ; ; ; ;A nutritional exam in applied to a random sample of individuals. Results are compared to expected means and proportions.