1. LESSON 5 - STATISTICS & RESEARCH STATISTICS – USE OF MATH TO ORGANIZE, SUMMARIZE, AND INTERPRET DATA.

2. DESCRIPTIVE STATISTICS – USE TO ORGANIZE AND SUMMARIZE DATA

3. TO DESCRIBE DATA: Range – The gap between the lowest and highest scores. Variation – How similar or diverse the scores are. Standard Deviation – How much scores vary around the mean, or average score.

4. QUANTIFY THE STRENGTH OF AN ASSOCIATION Correlation – Exists when two variables are related to each other. Correlation Coefficient – Numerical index of the degree of relationship between variables.  1. Direction (+/-)  2. how strongly related

5. POSITIVE VS. NEGATIVE CORRELATION

6. STRENGTH OF THE CORRELATION 0 means no relationship between variables +1.00 or -1.00 = perfect correlation All correlations fall between -1.00 and +1.00 Higher correlation = more accurate prediction. Correlation is not equivalent to causation!!!

7. INFERENTIAL STATISTICS – USED TO INTERPRET DATA AND DRAW CONCLUSIONS. Used to evaluate the possibility that the results were a fluctuation of chance. Statistical Significance – Probability of observed findings happening by chance is very low.  Very low = less than 5 of 100, or.05

8. FOR A LANGUAGE TEST WITH NORMALLY DISTRIBUTED SCORES, THE MEAN WAS 70 AND THE STANDARD DEVIATION WAS 10. APPROXIMATELY WHAT PERCENTAGE OF TEST TAKERS SCORE 60 AND ABOVE? A.16 B.34 C.68 D.84 E.95

9. FOR A LANGUAGE TEST WITH NORMALLY DISTRIBUTED SCORES, THE MEAN WAS 40 AND THE STANDARD DEVIATION WAS 15. APPROXIMATELY WHAT PERCENTAGE OF TEST TAKERS SCORE 70 AND ABOVE? A.2 B.14 C.16 D.50 E.80

10. IF YOU ARE GIVEN VARIANCE… Standard Deviation is just the square root of Variance. Ex. Variance is 100, what is standard deviation?  5  10  25  50  100

11. NORMAL DISTRIBUTION = “THE BELL CURVE”

12. YO DUDE – WE’RE SKEWED!

13. WHAT’S THE DIFFERENCE?