Descriptive Statistics Flashcards
Characteristics that may differ (vary) among individuals
Variables
values of variables for individuals (singular datum)
data
an individual; symbolize: x1, X2, …Xn (n=sample size)
case/ovservation
all individuals of a specified part of the universe (cf biological definition)
population
subset of population; used to make inferences regarding the population (usually unknown)
sample
physical measurement error, and a difference between the real population value and the estimates (from sample data) of the population value.
error
all the individuals have equal probability of being sampled
randomness
value of one case does not affect the value of other cases (exception e.g., repeated measures on same individual - dependence by design)
independence
values not quantitative or ranked; no mathematical or value relationship, mutually exclusive categories (e.g. male/female); 1 variable type: categorical
categorical scale (nominal)
relative differences( eg greater than/less than); no mathematical relationships between values (eg, small/medium/large; highly active/not active; health status: 1=healthy, 2=ill, 3=sick, 4=hospitalized, 5= dead, 1 variable type: ranked
Ranked scale or Ordinal
mathematically defined distance btween values; quantitative, absolute zero point; 2 variable type, may convert ration data to ranked/categorical data (not visa versa)
Ratio scale
may assume only certain values within given range(eg, 1,2,3,4)
discrete
may assume any value within given range (1.0,2.0,2.34,2.344, ect)
continuous
mathematically defined distance between values; quantitative; arbitrary zero point, (eg Celsius temperature scale), 2 variable types, may convert interval data to ranked/categorical data(not vice versa)
Interval scale
