Question

You want to measure your resting pulse rate. You might count the number of beats in five seconds and multiply by 12 to get beats per minute.

Consider counting the number of beats in 15 seconds and multiplying by 4 to get beats per minute. In what way will this improve the reliability of your measurement?

a. This measurement will likely have a smaller variance, since you're multiplying by 4 instead of 12.

b. You are less likely to make a counting error, since you're counting to a smaller number.    

c. It is a more systematic method of measurement.

d. This method eliminates the bias present in the first method.

e. Your pulse is more likely to be consistent over a longer period of measurement.

Answer 1

a. This measurement will likely have a smaller variance, since you're multiplying by 4 instead of 12.

Var(aX) = a² * Var(X)