# stats: plz need help

• September 12th 2007, 01:14 PM
harry
stats: plz need help
A person scores 81 on a test of verbal ability and 6.4 on a test of quantitative ability. For the verbal ability test, the mean for people in general is 50 and the standard deviation is 20. For the quantitative ability test, the mean for people in general is 0 and the standard deviation is 5. Which is this person’s stronger ability: verbal or quantitative? Explain your answer to a person who has never had a course in statistics.
• September 12th 2007, 02:41 PM
TKHunny
Quote:

Originally Posted by harry
A person scores 81 on a test of verbal ability and 6.4 on a test of quantitative ability. For the verbal ability test, the mean for people in general is 50 and the standard deviation is 20. For the quantitative ability test, the mean for people in general is 0 and the standard deviation is 5. Which is this person’s stronger ability: verbal or quantitative? Explain your answer to a person who has never had a course in statistics.

Well, person who never has had statistics, you are going to have to learn one word. You may heave heard it before in a different context. I submit to you NORMALIZE.

In this case, it means to invent a comparative measure so that different types of scores can be compared. Fortunately, the statistics wizards have done it already. I like to describe it to persons who never have had statistics as "How far off is it, compared to how far off it's supposed ot be?"

Verbal

Score 81
Mean 50
Standard Deviation 20
How far off is it? 81 - 50 = 31
Compare to how far off it is suppsed to be. 31/20 = 1.55
Conclude: Well, then this person is 1.55 "supposed-to-be"s above where the average Joe is.

Quantitative

Score 6.4
Mean 0
Standard Deviation 5
How far off is it? 6.4 - 0 = 6.4
Compare to how far off it is suppsed to be. 6.4/5 = 1.28
Conclude: Well, then this person is 1.28 "supposed-to-be"s above where the average Joe is.

You may find more technical terms, such as z-score, Normal Deviation, something like that, but I promised that you would have to learn only one word, so I'll leave it at that. :) There might even be a formula sitting about, somehting like $\frac{x-\mu}{\sigma}$, but again, I don't want to muddy the waters. ;)