# MandysNotes

## 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

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?

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.

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