Independent/Dependent variables - ANSWER Independent= intervention
Dependent= outcome of interest, change in response to an intervention
Discrete variables - ANSWER only take a limited number of values within a given range, qualitative values
Two types: nominal and ordinal
Types of random v...
Independent/Dependent variables - ANSWER Independent= intervention
Dependent= outcome of interest, change in response to an intervention
Discrete variables - ANSWER only take a limited number of values within a given
range, qualitative values
Two types: nominal and ordinal
Types of random variables - ANSWER Discrete (nominal, ordinal);
Continuous (interval, ratio)
Nominal variables "named" - ANSWER categorical or grouped with NO specific
order, no indication of relative severity, no numerical or quantitate value.
Ex. sex (M/F), mortality (dead/alive), disease presence (Y/N), race, marital status
Ordinal variable - ANSWER ranked in a specific ORDER but no consistent
magnitude.
Ex. NYHA class, severity scores, disease classes
Continuous variables - ANSWER take any value within a given range, counting
variables, quantitative values
Two types: interval and ratio
, Interval variable - ANSWER values ranked in a specific order with a consistent
change in magnitude between units, NO absolute zero
Ex. temperature (F)
Ratio variable - ANSWER values ranked in a specific order with a consistent change
in magnitude between units, Absolute zero
Ex. temperature (kelvin), heart rate, BP, time, distance, height, weight
Types of statistics - ANSWER Descriptive and inferential
Descriptive statistics - ANSWER Describes numerically/visually the data collected
from the study, confined to the study population only.
Ex. mean, median, mode
Mean - ANSWER Average, used for continuous and normally distributed data (not
ordinal data), very sensitive to outliers
Median - ANSWER Midpoint, aka 50th percentile, used for continuous or ordinal
data, insensitive to outliers
Mode - ANSWER used for nominal, ordinal, or continuous. can have more than
one (bimodal, trimodal). does not describe meaningful distribution with a large
range of values.
Standard deviation - ANSWER measure of variability about the mean; square root
of the variance (average squared difference of each observation from the mean);
1SD=68% of sample values, 2SD=95%, 3SD=99%.
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