Descriptive Statistics I Flashcards
What are Categorical Variables?
Binary
Ordinal
Nominal
What are Numerical Variables?
Discrete
Continuous
What is Binary Data?
Binary – only two categories
e.g. present/absent, positive/negative, pregnant/not pregnant
What is Ordinal Data?
Ordinal – categories with natural order
e.g. stage of cancer, minimal/moderate/severe pain
What is Nominal Data/
Nominal – categories with no natural order
e.g. blood group, ethnicity
What is Discrete Data?
Discrete – observations can only take certain numerical values
e.g. number of children, number of GP visits
What is Continuous Data?
Continuous – observations can take any value within a range
e.g. age, height, body temperature
(the only restriction is the precision of the measurement tool)
What is Proportion?
Proportion – the number with a characteristic or outcome divided by the total number
Used to describe probability or risk (scale 0 to 1)
What is Percentage?
Percentage – the proportion multiplied by 100 (scale 0 to 100)
Often reported as N (%)
What are Odds?
Odds – the number with an exposure or outcome divided by the number without
The ratio of the probability of an event occurring to the probability of it not occurring (scale 0 to ∞)
What are Risk Differences?
Risk difference – difference in proportions between groups
if there is no difference this will be 0
What is Risk Ratio/Relative Risk?
Risk ratio AKA relative risk – risk in one group divided by the risk in the other
if there is no difference the ratio will be 1
Ratios > 1 indicate higher risk/odds in group of interest
Ratios < 1 indicate lower risk/odds in group of interest
What are Odds Ratio?
Odds ratio – odds in one group divided by odds in the other
if there is no difference the ratio will be 1
Ratios > 1 indicate higher risk/odds in group of interest
Ratios < 1 indicate lower risk/odds in group of interest
