Bias and sampling error

Bias and sampling error - Quiz

OK, it is time for a quiz. See if you can distinguish among measurement bias, sampling bias, and sampling error.

Match each example with the source of error which might make the point estimate quite different from the true population value

a)	The measuring tape on the height board was nailed to the backboard too high so every child is measured 5 cm too tall
b)	The sample size was small so the confidence intervals were wide.
c)	The members of one team misunderstood the directions and included children up to 10 years of age instead of only children 6-59 months of age.
d)	The scales were old and consistently measure 500 grams too light.
e)	One team decided they did not like travelling by foot, so they ignored their randomly selected list of clusters and only weight and measured children who lived in villages on the road.
Yes, you got them all. Excellent. No, you missed some. Just remember, a. If you have a small sample size resulting in poor precision, that is sampling error b. If you select the wrong sample so that it's not representative, that's sampling bias c. If your measurements are wrong, that's measurement bias Continue with the section; the subsequent explanation may clarify things for you. Your answer has been saved.