24 terms

observational unit

who or what is being studied

variable

characteristic of the observational unit

what are the two types of variables

quantitative and categorical

what are the two types of categorical variables

ordinal and nominal

quantitative variable

numerical value with units (ex: how many..?)

categorical ordinal

when the values of a categorical variable have an intrinsic (number) order (ex: class year)

categorical nominal

categorical variable with no order (ex: eye color)

population

the entire group of subject we want to learn about

sample

the smaller part of the population that you gather data from

response variable

dependent variabel; outcome or result of study

explanatory variable

independent variable; variable that we think explains the changes

confounding variable

outside variable that is correlated to both response and explanatory variable (ice cream and murders example)

correlation does not mean...

causation

parameter

characteristic used to describe a whole population

statistic

characteristic used to describe the sample

response bias

"leading questions" -worded to force a certain type of response; dishonest response to maintain image

volunteer response

those who respond chose to do so and tend to have stronger opinions

undercoverage

population is not evenly represented; created by sampling who ever is "convenient"

non-response bias

not everyone will respond to survey request

simple random sample (SRS)

each person in sample is assigned a number, numbers randomly generated to create sample size, then surveyed; results will vary with different samplings

stratified sampling

divide population into similar groups (strata) and then take a random sample from each group

cluster sampling

divide population into clusters (usually geographically based) then take SRS in each cluster

systematic sampling

create interval "K", select number between 1-K to start, pick every "K"th person

response bias

wording the question in a way that inflicts a certain response