Is high blood pressure dangerous

The Connection between Chi-Squared and

2 Proportion Tests

Is high blood pressure dangerous? Medical researchers classified each of a group of men as high or low blood pressure, then watched them for 5 years. (Men with systolic blood pressure 140mm Hg or higher were high; the others, low.) The following two-way table gives the results of the study. Is high blood pressure associated with a higher death rate?

_________________Died Survived TotalLow blood pressure 21 2655

2676

High blood pressure 55 3283 3338

Total

76

5938

6014

Is high blood pressure dangerous? Medical researchers classified each of a group of men as high or low blood pressure, then watched them for 5 years. (Men with systolic blood pressure 140mm Hg or higher were high; the others, low.) The following two-way table gives the results of the study. Is high blood pressure associated with a higher death rate?

_________________Died

Survived

TotalLow blood pressure 21 2655

2676

High blood pressure 55 3283

3338

Total

76

5938

6014Test of Independence: (Data in matrix [A], run X2)

H0: Blood pressure and death rate are not associatedHa: Blood pressure and death rate are associatedX2 = 8.86; df = 1; p = .0029.shows there is an association between blood pressure and death rate.

2 proportion z test: (comparing any set of 2 proportions in table)

H0: pL = pHwhere pL is the proportion of men with low blood pressure who died

Ha: pL ( pHand pH is the proportion of men with high blood pressure who diedz = 2.977; p = .0029shows there is a difference in the death rate for men with low blood pressure versus those with high blood pressure