Chi Square
Content
Analysis of Enumerative Data
By: BL
Learning Objectives
At the end of the two-hour lecture, the first year medical students shall be able to:
1. describe the experiment using enumerative data 2. compute hypothesis testing using the chi-square test 3. describe the 2 x 2 contingency table (i.e. the observe and expected tables) 4. state the significance of test using the contingencytable approach
Case-Control Study
Cancer A hypothesis has been proposed that breast cancer in women is caused in part by events that occur between the age at menarche (i.e. the age when menstruation begins) and the age at first childbirth. In particular, the hypothesis states that the risk of breast cancer increases at the length of this time interval increases. If this theory is correct, then an important risk factor for breast cancer is age at first birth. This theory would explain in part why breast cancer is age at first birth. This theory would explain in part breast cancer incidence seems to be higher for women in the upper socioeconomic groups, since they tend to have their children relatively late.
Data for the International Study Comparing the Age at first birth in Breast Cancer Cases with Comparable Controls
Hypothesis Testing
1. H0: There is no association between age at first birth and occurrence of breast cancer P1 = P2 2. H1: There is association between age at first birth and occurrence of breast cancer P1 P2
Cont of Hypothesis Testing
3. Level of significance ( ) = 0.05 x2(c-1)(r-1), Reject H0 if x2c>3.841
Cont of Hypothesis Testing
4. Test Statistic
Cont of Hypothesis Testing
5. Computation
Cont of Hypothesis Testing
6. Decision: Reject H0 7. Conclusion: There is association between age at first birth and occurrence of breast cancer
Test of Independence
Test of homogeneity
Hypothesis Testing
Cont. Of Hypothesis Testing
Question? Thank You
By: BL
Learning Objectives
At the end of the two-hour lecture, the first year medical students shall be able to:
1. describe the experiment using enumerative data 2. compute hypothesis testing using the chi-square test 3. describe the 2 x 2 contingency table (i.e. the observe and expected tables) 4. state the significance of test using the contingencytable approach
Case-Control Study
Cancer A hypothesis has been proposed that breast cancer in women is caused in part by events that occur between the age at menarche (i.e. the age when menstruation begins) and the age at first childbirth. In particular, the hypothesis states that the risk of breast cancer increases at the length of this time interval increases. If this theory is correct, then an important risk factor for breast cancer is age at first birth. This theory would explain in part why breast cancer is age at first birth. This theory would explain in part breast cancer incidence seems to be higher for women in the upper socioeconomic groups, since they tend to have their children relatively late.
Data for the International Study Comparing the Age at first birth in Breast Cancer Cases with Comparable Controls
Hypothesis Testing
1. H0: There is no association between age at first birth and occurrence of breast cancer P1 = P2 2. H1: There is association between age at first birth and occurrence of breast cancer P1 P2
Cont of Hypothesis Testing
3. Level of significance ( ) = 0.05 x2(c-1)(r-1), Reject H0 if x2c>3.841
Cont of Hypothesis Testing
4. Test Statistic
Cont of Hypothesis Testing
5. Computation
Cont of Hypothesis Testing
6. Decision: Reject H0 7. Conclusion: There is association between age at first birth and occurrence of breast cancer
Test of Independence
Test of homogeneity
Hypothesis Testing
Cont. Of Hypothesis Testing
Question? Thank You
