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.