1. Chapter 8 Simple Linear Correlation

6. 12.1 Linear correlation

7. Scatter Diagram : Fig. 7.1 Scatter diagram of systolic and diastolic blood pressures (mmHg) of 665 girls of 6 to 10 years old

11. Pearson’s product moment sample correlation coefficient r 7.2.2 Sample correlation coefficient

12. A measurement of linear relationship: 1) Whether there is a correlation If the correlation coefficient is 0 or not big enough -- no correlation 2) If correlation coefficient is big enough The direction of correlation? -- positive or negative The strength of correlation? high or not? -- Is the absolute value big enough? Complete correlation : +1 or -1,

13. Example 7.3 Calculate the correlation coefficient between the heights of father and son.

16. Question : If r =0.90, can you claim the two variables are correlated each other? Table 8 Critical values for r

20. Example 7.5 After getting , please find out a 95% confidence interval for population correlation coefficient .

23. Example 7.6 An etiology study on liver cancer has collected data on liver-cancer-specific death rate and the relative content of aflatoxin in certain food for 10 Counties. Putting the ranks into the formula of Spearman’s correlation coefficient

24. Table 9 Critical value for Spearman’s rank correlation coefficient 7.4.2 Hypothesis test for (1) Checking a special table (Table 9) P <0.02 and it is significant