Practice Quiz-Lecture 10 Flashcards
Oncologists studied PD-L1 expression (present versus absent) in a sample of 800 independent metastatic melanoma tumors. PD-L1 expression is a
categorical variable
-Because PD-L1 expression is given as absent or present
Oncologists studying PD-L1 expression (present versus absent) in a sample of 800 independent metastatic melanoma tumors found that PD-L1 expression was present in 200 tumors and absent in the remaining 600 tumors. The proportion of PD-L1 presence is
200/800=0.25
Oncologists studying PD-L1 expression (present versus absent) in a sample of 800 independent metastatic melanoma tumors found that PD-L1 expression was present in 200 tumors and absent in the remaining 600 tumors. The odds of PD-L1 expression is
0.25/0.75=0.33
Epidemiologists examined the genotypes of the V60L locus in the MC1R gene in 1099 melanoma patients. 838 patients had VV genotype, 234 had VL genotype and 27 had LL genotype. What type of variable is V60L genotype?
categorical variable
Epidemiologists examined the genotypes of the V60L locus in the MC1R gene in 1099 melanoma patients. 838 patients had VV genotype, 234 had VL genotype and 27 had LL genotype. What type of variable is V60L genotype?
27/1099=0.025
To study the association between genotype in the SNP rs749292 in the CYP19A1 gene and endometrial cancer, epidemiologists recruited 1697 women without endometrial cancer and 3954 women with endometrial cancer. Among women without endometrial cancer, 364 had the AA genotype. Among women with endometrial cancer, 755 had the AA genotype. The prevalence of AA genotype in women without and with endometrial cancer are:
Without: 364/1697 = 0.214, With: 755/3954 = 0.19
The prevalence of flu vaccination among SPH students is 25%. The odds of flu vaccination among SPH students is:
0.25
The odds of coronary heart disease among women and men are 2 and 4, respectively. The odds ratio, defined as the odds of coronary heart disease among men relative to women is
0.5
When there is no association between sex and coronary heart disease, the odds of coronary heart disease among men relative to women is:
0.5
The prevalence of diabetes among women in city A is 20%. There is no association between diabetes and sex in city A. The prevalence of diabetes among men in city A is
20%
-When there is no association between diabetes and sex, the prevalence in men and women are the same
When comparing the association between bladder cancer (with two groups: have cancer or do not have cancer) and smoking status (with 3 groups: never smoked, past smoker and current smoker), a researcher organizes the data with smoking status in rows and bladder cancer status in columns. This is an RxC contingency table, where R and C are
3 and 2
-Smoking status row, and there are 3 smoking groups. So there are 3 rows. Cancer status is column, and there are 2 cancer statuses. So there are 2 columns. Hence, 3x2
When comparing the association between bladder cancer (with two groups: have cancer or do not have cancer) and smoking status (with 3 groups: never smoked, past smoker and current smoker) using a chi-square test, the sampling distribution of the test statistic is __________ with ______ degrees of freedom. What are the values for the blanks
chi squared and 2 df
Epidemiologists are comparing the association between age (<50 years and >= 50 years groups) and breast cancer (presence or absence of breast cancer) in women using a chi-square test. When there is no association between age and breast cancer, the odds of breast cancer among women of age < 50, relative to the odds of breast cancer among women of age >= 50 will be equal to
1
