day 3 Flashcards
What is risk?
the probability (usually statistical probability) that an event will occur in a group, whether it be a good or a bad event.
What is the probability is a player owns 1 out of 4 totl cards
The probability is an ordinary fraction (e.g., 1/4) that can also be expressed as a percentage (e.g., 25%) or as a proportion between 0 and 1 (e.g., p = 0.25).
What is the definition of Relative Risk (or Risk Ratio)?
The term ‘risk ratio’ is sometimes used because RR is calculated by dividing the probability of an event occurring for one group by the probability of an event occurring for a second group.
What is the deifiniton of odds
Odds are ratios of a player’s chances of losing to his or her chances of winning, or the average frequency of a loss to the average frequency of a win.
What are the odds in this example?
imagine we bought three tickets the probability of winning would be 3 in 4,
The odds would be 75 to 25. We can simplify this to 3 to 1. This means that the winning event is three times more likely to occur than not occur.
What are the distinctions between RR, OR , AR
RR is used to compare the risk in two different groups of people (e.g. smokers and non-smoker), usually used in prospective cohort studies.
OR is a measure of association between an exposure and an outcome (e.g. smoking and cancer), usually used in case-control studies and sometime in cohort studies (where the incidence is less than 10%).
AR is an individual risk of developing a disease over a time period (e.g. smokers and cancer), usually used for the number of events (such as a disease) that occurred in a group, divided by the number of people in that group.
What is the definition of relative risk?
RR is used to compare the risk in two different groups of people (e.g. smokers and non-smoker), usually used in prospective cohort studies and can increase or decrease the risk
What is the definition of ods ratio?
OR is a measure of association between an exposure and an outcome (e.g. smoking and cancer), usually used in case-control studies and sometime in cohort studies (where the incidence is less than 10%).
what is the definition of adverse risk
AR is an individual risk of developing a disease over a time period (e.g. smokers and cancer), usually used for the number of events (such as a disease) that occurred in a group, divided by the number of people in that group.
What is the definition of relative risk reduction RRR
describe the decrease in probability of an event occurring due to a lifestyle change or treatment.
When is RR used
statistical analysis of data from experimental, cohort and cross-sectional studies, to estimate the strength of the association between treatments or risk factors, and outcome. The RR value is used to test whether differences between groups are significant e.g. treatment and placebo or disease versus control. (we will discuss this in more detail later – essentially, we cannot really use RR in a significance test but we have a ‘work-around’ of sorts).
How can RR be calculated from AR?
RR= AR exposed/AR unexposed
What is probability useful for and not useful for?
- Useful to predict how often an outcome will occur
- Not useful to predict exactly when an outcome will occur
What is relative risk?
Ratio of probability of outcome occurring in an exposed group to the probability of the outcome occurring in an unexposed group
Are RR and OR interchangeable
- No
- OR can be used as an estimate of RR if rare disease
- Odds ratio is an overestimate if common disease
