MandysNotes

Z-Scores

Z-Scores (4)

Saturday, 23 January 2010 00:00

Z-Score Chart

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This is the standard type of table you will see in  most Statistics Textbooks. 

If you are allowed to use a calculator for calculating Z-scores and areas under the curve, I suggest you glance at this to get familiar with what it is, and MOVE ON. 

If you are NOT allowed to use a calculator, it would be a good idea to get friendly with this table - and FAST.  During an exam, the last thing you want to be worrying about is figuring out how to find your way around this thing!

 

Friday, 22 January 2010 21:36

Z-Score Example Problems

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Disclaimer: I did not create nor do I own these videos. I have simply embedded them, courtesy of YouTube.

This is a great video because it gives walk-throughs of z-score calculations from homework problems. You may not have these exact problems, but the same concepts can be applied to your own work!

 

These examples rely on the Z-Score Formula:

MEMORIZE this formula, make sure you know it COLD!

If you do not know what the "m-like" symbol or the "o" with a tail are, check out What's with the Greek?

Friday, 22 January 2010 20:51

Calculating a Z-Score

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Sometimes we need a standardized scale to measure a value's distance from the center. 

A Z-score indicates how many STANDARD DEVIATIONS a value is from the mean. 

 

The official formula is:

 

So let's say the MEAN is 100 and the Standard Deviation is 15. 

 

If you are given a value of 132, you just plug that into the formula above. 

132 - 100 = 32

32 / 15 = 2.133 

 

VOILA - Your Z-Score is 2.133

 

Friday, 22 January 2010 18:35

What is a Z-Score?

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Disclaimer: I did not create nor do I own these videos.  I have simply embedded them, courtesy of YouTube. 

It is very important that you understand what a Z-score represents as well as how to obtain a Z-score manually, by hand.  

HOWEVER, you should also know how to get around your TI-83 or 84 series calculator.  Use it to find a Z-Score and the AREA under a curve

 

 

And here is another, more comprehensive overview of Z-Scores:

NOTRad