IDS 270 Exam 1 Vocab

random variable

1. produces only numbers 2. driven by a random (or stochastic) process

multi stage sampling

basically practicing stratified sampling repeatedly to get a final sample.

double blind experiment

neither the researcher nor the subject knows who is receiving which treatments in a study

response biaas

not answering truthfully when asked question about sensitive subject

statistical significance

a finding that is unlikely to be due to random chance alone

stratified sampling

first breaking the population into natural segments (strata) and then using random sampling within the strata

convenience sampling

people are selected to be in a sample because of convenience or low expense.

subjects

people involved in the experiment

voluntary response sampling

people volunteer to give data for a study.

Experiment

impose a treatment on people and then observe their behavior or ask questions

simple random sampling

label all the people in the population with a number. have a computer select a set of random numbers in that range. people labeled with the number are selected for the sample. Everyone has the same chance to get chosen.

S

sample space; the set of everything that can happen in a random phenomenon

bias

systematically favoring a certain outcome from research

Population

the set of everything

conditional distribution

the values for one variable after holding another variable to a single value

marginal distribution

the values for one variable if we ignore the categories of the other variable.

placebo effect

when a subject thinks that they are feeling better simply because they are involved in a sstudy

Non response

when an individual selected for the sample does not provide info

undercoverage

where some members of the population cannot be selected for the sample

Completely randomized design

within an experiment, use random sampling to assign the subjects to the different treatments

random or stochastic phenomenon

the outcome of any one trial is unknown, but after a large number of trials the expected pattern is seen.

explanatory variable

(aka independent variable) the thing we have be different for different individuals in order to measure the association with the response variable

response variable

aka dependent variable

treatment

a unique combination of levels of factors given to a set of subjects

discrete variable

a variable that can only take on a set number of values. (the number spots on a die)

continuous variable

a variable that has values that continue smoothly on a scale. numbers between 0 and 2

finite sample space

a way to assign probabilities to a discrete variable

infinite sample space

a way to assign probabilities to ranges of events for a continuous varibale

parameter

a number that describes the population. it is a fixed number but in practice we do not know its value. ( mean and standard deviation

sample

a small group pulled from the population

Observational study

observing the behavior or ask people questions as they are going about their day to day lives.

Confounded variables

two variables where the effect of one on the dependent variable cannot be separated from the effect of the other.