Understanding Reliability and Validity

Students want to study the effect of exercise on pulse rate. They test this by doing different numbers of jumping jacks and then measuring their pulse rates. They divide into four groups; one group does jumping jacks for one minute, a second jumps for two minutes, a third for three, and a fourth does not jump.

Which of the following would be a valid measure of pulse rate in this study?

	a)	Counting the number of jumping jacks for one minute.
	b)	Counting the number of heart beats in one minute.
	c)	Counting the number of jumping jacks done by each group.
	d)	Counting the number of exercises done by each person.
Counting the number of heartbeats is a valid measure.This is not a valid measure of the effect of exercise on pulse rate.Your answer has been saved.

You take the blood pressure of a 64 year old man with a cuff designed for a child. You repeat your measurement three times and get similar readings. This measurement is reliable.

	a)	True
	b)	False
The measurement is reliable because you get similar readings each time.Even though the cuff may not be the appropriate one and thus the test not valid, it is reliable.Your answer has been saved.

At target practice, Tim shoots 15 bullets at the bull's eye. The bullets produce a pattern like this:

Tim's shooting is:

	a)	Reliable, not valid.
	b)	Valid, not reliable.
	c)	Neither reliable nor valid.
	d)	Both reliable and valid.
Please select an answerYes, Tim puts his bullets in the same area of the target making his shooting reliable, but he is aiming at the bulls eye.Tim is aiming at the bull's eye but shoots elsewhere, thus his shooting is not valid.Tim is aiming at the bull's eye but misses. His shots are in a reliable pattern elsewhere.Tim's shooting is consistent/reliable, but not where he is aiming.

Suppose Tim's shots produced a pattern like this:

Tim's shooting is:

	a)	Reliable, not valid.
	b)	Valid, not reliable.
	c)	Neither reliable nor valid.
	d)	Both reliable and valid.
Assuming Tim is trying to hit the target, this pattern would be both reliable and valid.If he produced this pattern, his shooting would be reliable and valid.Your answer has been saved.

In order to be valid, a test must be reliable.

	a)	True
	b)	False
Reliability is prerequisite to validity.Reliability is prerequisite to validity.Your answer has been saved.

Non-random errors affect only validity.

	a)	True
	b)	False
Yes, non-random errors affect validity.Non-random errors affect only validity.Your answer has been saved.