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## #1 2006-07-09 12:24:55

babyangel1972
Member
Registered: 2005-12-12
Posts: 18

### Help...

Let's say a student scored 45 on a math achievement test for which the mean was 36 and the standard deviation was 6.  Judging on the basis of this performance, what score would you predict for her on a standardized test for which the mean is 100 and the standard deviation 15?

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## #2 2006-07-09 17:40:39

George,Y
Member
Registered: 2006-03-12
Posts: 1,306

### Re: Help...

45-36=9 he is 9 points above mean.
9/6=1.5 he is 1.5 times of stdev above mean.
And this should always holds, regardless of the value of mean or stdev.
Why?
Suppose you can add all scores with 2 points, his will remain 9 points ahead.
Suppose you can multiply all scores by 2, his will be 18 points above mean, still 1.5 times of stdev.

Suppose he does as well as in the former test, he will still get a score 1.5 times of stdev above mean. This time, mean=100, stdev=15, he will get 122 or 123.

X'(y-Xβ)=0

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## #3 2006-07-10 15:44:14

babyangel1972
Member
Registered: 2005-12-12
Posts: 18

Thank You!

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## #4 2006-07-13 01:38:13

George,Y
Member
Registered: 2006-03-12
Posts: 1,306

You are welcome

X'(y-Xβ)=0

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## #5 2013-01-27 07:55:16

brodr7630
Member
Registered: 2013-01-27
Posts: 1

### Re: Help...

Let's say a student scored 45 on a math achievement test for which the mean was 36 and the standard deviation was 6. Judging on the basis of this performance, what score would you predict for her on a standardized test for which the mean is 100 and the standard deviation 15?

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## #6 2013-01-27 10:34:19

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,766

### Re: Help...

Look at post #2.

Bob

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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