Stat

Front 1

Observes individuals and measures variables of interest, but does not attempt to influence the response (i.e. we simply observe and record outcomes). The purpose is to describe a group or situation

Back 1

Observational study

Front 2

What are the two ways to gather data?

Back 2

1. Observational data
2. Experiments

Front 3

Deliberately impose some treatment on the individuals in order to observe their responses. The purpose is to study whether the imposed treatment causes a change in the response.

Back 3

Experiment

Front 4

is tells us how to choose the sample (spoonful) from the population (bowl).

Back 4

Sampling design

Front 5

is taken by sampling the easiest to reach members of the population. These samples are often biased, that is, they systematically favor certain outcomes.

Back 5

Convenience sample

Front 6

consists of people who choose to respond. These are usually biased since people with strong opinions are more likely to answer

Back 6

Voluntary response sample

Front 7

N individuals are chosen from the population in such a way that each individual is equally likely to be chosen

Back 7

Simple random samples

Front 8

First classify the population into groups of similar individuals, called strata. Then, choose a separate SRS in each strata and combine all the SRSs to form the full sample

Back 8

Stratified random samples

Front 9

Occurs when some groups of the population are left out of the process of choosing the sample.

Back 9

Undercoverage

Front 10

Occurs when a chosen individual cannot be contacted or refuses to participate. This is a more serious bias and often reaches 50% or more in a sample.

Back 10

Nonresponse