Exam #1: Biostatistics V Flashcards
What is a proportion?
of observations/ whole
*****Note that this is the same things as the probability
What is a rate? How does this relate to a proportion?
- Rates are similar to proportions except a multiplier is used
- Rates have a time reference i.e. are calculated over a period of time
What are vital statistics?
Demographic statistics that describe the health of a population
What are the most widely used vital statistics?
- Mortality rates
- Morbidity rates
What is a crude mortality rate?
of all deaths in a region, in a given year/ total population in that region/ year
What is a specific mortality rate?
This relates to a specific population death rate e.g. women, men…etc.
What is a morbidity rate?
individuals who develop a disease in a period of time/ region/ total
What does the morbidity rate define?
Prevalence or prevalence rate
What is the difference between prevalence and incidence?
Prevalence= # cases/ region/ time
Incidence= # of NEW cases
Why are morbidity and mortality rates adjusted?
There may be confounding factors in a population
*****E.g. mortality rate as a measure of health in a very old population should be corrected for
What is the experimental event rate (EER)?
How often an event occurs within the experimental group (non-control group) of an experiment
What is the formula for calculating an EER?
A/ A + B
What is the control event rate (CER)?
How often an event occurs within the control group of an experiment
What is the formula for calculating a CER?
C/ C + D
What does absulate risk reduction (ARR) mean?
Change in risk of a given activity or treatment in relation to a control activity or treatme
What is the formula for calculating the ARR?
EER - CER
What is the NNT?
Number of patients who need to be treated to prevent one additional bad outcome
How do you calculate the NNT?
NNT= 1/ARR i.e.
NNT= 1/ (EER - CER)
What is the relative risk reduction?
Amount of risk reduction relative to the baseline risk
What is the formula for the relative risk reduction?
(EER - CER)/ CER
OR
A/ (A+B) / C/ (C+D)
What is relative risk?
Ratio of incidence of disease in people exposed to risk factor vs. incidence in people without risk factor
What is the odds ratio?
Odds that a person with disease is exposed to a risk factor vs. odds of a person without the disease exposed to the same factor
What types of studies use relative risk and odds ratio?
Relative risk= cohort
Odds ratio= case-control
What does a RR or OR that is
Protective exposure
What does a RR or OR that is >1 mean?
Risky exposure
What does a RR or OR =1 mean?
No effect of exposure
Do the distributions of RR or OR follow the theoretical probability distribution?
No
How can you transform RR or OR to follow a normal distribution?
Take the natural log of RR or OR
Calculate EER, CER, ARR, NNT, RRR, RR, and OR in the example provided in the ppt. Interpret the results of the RR and OR.
N/A
