1. Myers EXPLORING PSYCHOLOGY (6th Edition in Modules)
Appendix A
Statistical Reasoning in Everyday Life
James A. McCubbin, PhD
Clemson University
Worth Publishers

2. Statistical Reasoning
Mode
the most frequently occurring score in a distribution
Mean
the arithmetic average of a distribution
obtained by adding the scores and then dividing by the number of scores
Median
the middle score in a distribution
half the scores are above it and half are below it

3. Statistical Reasoning
Our Brand Brand Brand
Brand X Y Z
100% 99 98 97 96 95
Percentage
still functioning
after 10 years
Brand of truck

4. Statistical Reasoning
Our Brand Brand Brand
Brand X Y Z
100% 90 80 70 60 50 40 30 20 10
Percentage
still functioning
after 10 years
Brand of truck

5. Statistical Reasoning
Range
the difference between the highest and lowest scores in a distribution
Standard Deviation
a computed measure of how much scores vary around the mean

6. Statistical Reasoning
A Skewed Distribution 90
475
710 70
Mode Median Mean
One Family
Income per family in thousands of dollars

7. Statistical Reasoning
The Normal Curve

8. Statistical Reasoning
Correlation Coefficient
a statistical measure of the extent to which two factors vary together, and thus how well either factor predicts the other
Positive- scores go up and down together
Negative- one score falls as the other rises
Regression Toward the Mean
the tendency for the extremes of unusual scores or events to fall back (regress) toward the average

9. (positive or negative)
Correlation
Indicates direction
of relationship
(positive or negative)
Correlation
coefficient
r = +.37
Indicates strength
of relationship
(0.00 to 1.00)

10. Correlation Perfect positive correlation (+1.00)
No relationship (0.00)
Perfect negative
correlation (-1.00)

11. Height and Temperament of 20 Men
Correlation
Height and Temperament of 20 Men 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 80 63 61 79 74 69 62 75 77 60 64 76 71 66 73 70 68 90 42 81 39 48 72 57 30 84
Subject
Height in
Inches
Temperament

12. Correlation

13. Making Inferences Statistical Significance
a statistical statement of how likely it is that an obtained result occurred by chance