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
