General Flashcards
Formula for incidence rate:
No. of new cases of disease/total person-time at risk
Presented as something like “cases per 100 people” - just multiply result by 100
Formula for relative risk:
(No. of cases per exposure group/total no. of individuals in that exposure group)/(no. of cases in non-exposed group/total no. of individuals in non-exposed group)
Formula for odds ratio:
(No. of cases in exposed group/no. of non-cases in that group)/(no. of cases in non-exposed group/no. of non-cases in that group)
Risk difference formula:
(No. of cases in exposure group/total no. of individuals in that group) - (no. of cases in non-exposure group/total no. of individuals in that group)
What is the standard deviation?
The square root of the variance
Describe the sensitivity of a diagnostic test
- Pr(B|A)
- The probability that a person with the disease has a positive test result
Describe the specificity of a diagnostic test
- PR(not B|not A)
- The probability that a person without the disease has a negative test result
Describe a false positive fraction in a diagnostic test
1 - specificity OR Pr(B|Not A)
Describe a positive predictive value in a diagnostic test
- Pr(A|B)
- The proportion of patients with positive test results who have the disease
Describe a negative predictive value in a diagnostic test
- Pr(not A|not B)
- The proportion of patients with negative test results who don’t have the disease
When π is not known…:
It is estimated using p=X/n, the proportion of successes in the sample data
The mean of a binomial distribution (nπ) is estimated by:
np
What is the multiplier for 95% CI?
1.96
What is the multiplier for 99% CI?
2.58
Type I error:
Rejecting H0 when H0 is actually true (false positive)
