繼續研讀 Applied Statistics for The Behavioral Sciences

• 10:20-13:00
• Computer Example: The Survey of High School Seniors Data Set
• Standard Scores
• The z score indicates the number of standard deviations a corresponding raw score is above or below the mean.
• Properties of z Scores
1. The distribution of standard scores preserves a shape similar to that of the original distribution of raw scores.
2. The mean of the distribution of z scores will always equal 0 regardless of the value of the mean in the raw score distribution.
3. The variance of the distribution of z scores always equals 1. Since the standard deviation is the square root of the variance, the standard deviation will also equal 1.
• Weighted averages
• When developing a composite score from two or more individual scores, first transform the individual scores into standard scores. Then apply the weights to generate the weighted score. 
• Transformed Standard Scores
• To transform a distribution of scores into a distribution with a desired mean and standard deviation, multiply the z scores by the desired standard deviation and add the desired mean.
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