stats Flashcards
variable
A variable is a characteristic or attribute that can assume different values.
random variables
A variable whose values are determined by chance are called random variables.
population
A population consists of all subjects (human or otherwise) that are being studied.
Descriptive statistics
Descriptive statistics consists of the collection, organization, summarization, and presentation of data.
Inferential statistics
Inferential statistics consists of generalizing from samples to populations, performing estimations and hypothesis tests, determining relationships among variables, and making predictions.
Hypothesis testing
Hypothesis testing is a process for evaluating claims about a population, based on information obtained from a sample.
qualitative variable
A qualitative variable is a variable that has distinct categories according to some characteristic or attribute.
quantitative variable
A quantitative variable is a variable that can be counted or measured.
discrete variable
A discrete variable assumes values that can be counted, or assigned values such as 1, 2, 3 and so on.
continuous variable
A continuous variable assumes values within an interval, and can have infinitely many values between any two specific values. They are obtained by measuring. They often include fractions or decimals.
boundary
The boundary of a number is the class of values in which the data value would fall before being rounded.
There are four common measurement scales used to classify variables.
Qualitative variables can have the nominal level of measurement or the ordinal level of measurement.
Quantitative variables can have the interval level of measurement or the ratio level of measurement.
nominal level of measurement
The nominal level of measurement classifies data into mutually exclusive (non-overlapping) categories in which there is no natural order or ranking of the categories.
ordinal level of measurement
The ordinal level of measurement classifies data into categories that can be ranked; however, precise differences between the ranks do not exist.
random sample
A random sample is a sample in which all members of the population have an equal chance of being selected.
systematic sample
A systematic sample is a sample obtained by selecting every kth member of the population, where k is a counting number.
cluster sample
A cluster sample is obtained by dividing the population into sections or clusters and then selecting one or more clusters at random, and using every member of the selected cluster or clusters as the sample.
stratified sample
A stratified sample is a sample obtained by dividing the population into subgroups or strata according to some characteristic relevant to the study. Then subjects are selected at random from each subgroup.
convenience sample
A convenience sample is a sample chosen out of convenience, with no randomization. For example, a restaurant manager asks everyone at the restaurant one evening to rate the service on a scale from 1 to 5.
treatment group
The treatment group of an experimental study is the group that receives the new drug or treatment that the study is evaluating.