Outline - Z-Scores: Lecture 3, Part 1 (00:60)
In this video lecture, Professor Naomi Lowe explains Z-scores, how to use Excel for easy calculations, and introduces the normal curve.
Using Excel (04:36)
Lowe demonstrates how to compute the mean, variance and standard deviation using Excel.
A Z-score is the number of standard deviations of a raw score away from the mean.
Calculating Z-Scores (07:52)
To calculate a Z-Score, first, subtract the raw score from the mean and divided that value by the standard deviation. Positive numbers indicate the Z-score is above the mean whereas a negative value is a Z-Score below the mean.
Calculating Raw Scores From a Z-Score (02:34)
Lowe provides the formula and logic behind calculating the raw score with only the Z-Score and standard deviation.
Distribution of Z-Scores (03:16)
The mean for Z-scores will always be 0 and then standard deviation will always be 1.
The Normal Curve (06:50)
The normal curve is a symmetrical, unimodal, bell-shaped curve. The normal curve occurs frequently in nature. Special properties of the normal curve include 100 percent of all observances, the tails extend indefinitely, and 96 percent of observations fall within plus or minus 3 standard deviations of the mean.
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