For this exercise, you will be navigating problem 10.13, Sexually Transmitted Disease, and problem 10.15, Ophthalmology, both on page 439 of the textbook. Here are a few helpful hints: For problem 10.13, construct a 2x2 contingency table of the data presented in the problem, then use a chi-square test with Yates correction to determine if there is an association between row and column classifications.For problem 10.15, construct a 2x3 contingency table of the data presented in the problem, compute the table of expected values, and then use the chi-square test to evaluate.
Sexually Transmitted Disease
Suppose researchers do an epidemiologic investigation of people entering a sexually transmitted disease clinic. They find that 160 of 200 patients who are diagnosed as having gonorrhea and 50 of 105 patients who are diagnosed as having nongonococcal urethritis have had previous epi- sodes of urethritis
*10.13 Are the present diagnosis and prior episodes of urethritis associated?
Cancer 10.14 A 1980 study investigated the relationship between the use of OCs and the development of endometrial cancer [9].The researchers found that of 117 endometrial-cancer patients, 6 had used the OC Oracon at some time in their lives, whereas 8 of the 395 controls had used this agent. Test for an association between the use of Oracon and the incidence of endometrial cancer, using a two-tailed test.
Ophthalmology Retinitis pigmentosa is a disease that manifests itself via different genetic modes of inheritance.Cases have been documented with a dominant, recessive, and sex-linked mode of inheritance.It has been conjectured that mode of inheritance is related to the ethnic origin of the individual. Cases of the disease have been surveyed in an English and a Swiss population with the following results: Of 125 English cases, 46 had sex-linked disease, 25 had reces sive disease,and 54 had dominant disease.Of 110 Swiss cases,1 had sex-linked disease,99 had recessive disease and 10 had dominant disease.
*10.15 Do these data show a significant association be- tween ethnic origin and genetic type?