Information coming from observations, counts, measurements, or responses.
The science of collecting, organizing, analyzing, and interpreting data in order to make decisions.
The collection of all outcomes, responses, measurements, or counts that are of interest.
A subset of a population.
A numerical measurement describing a population characteristic.
A numerical measurement describing some characteristic of a sample.
The branch of statistics that involves the orginization, summarization, and display of data.
The branch of statistics that involves using a sample to draw conclusions about a population.
Data that consists of attributes, labels, or nonnumerical entries.
Data that consists of numerical measurements or counts.
Nominal Level of Measurement
Qualitative only. Data at this level are categorized using names, labels, or qualities. No mathematical computations can be made at this level.
Ordinal Level of Measurement
Data at this level are qualitative or quantitative. Data at this level can be arranged in order, or ranked, but differences between data entries are not meaningful.
Interval Level of Measurement
Data at this level can be ordered, and you can calculate meaningful differences between data entries. At this level, a zero entry simply represents a position on a scale; the entry is not an inherent zero.
Ratio Level of Measurement
Data at this measurement are similar to data at the interval level, with the added property that a zero entry is an inherent zero. A ratio of two data values can be formed so that one data value can be meaningfully expressed as a multiple of another.
Observes individuals and measures variables of interest but does not attempt to influence the responses.
The act of conducting a controlled test or investigation.
A specific experimental condition applied to the units.
The group that does not receive the experimental treatment.
Individuals on whom an experiment is performed.
Something presented as a drug, but having no actual effect.
The act of imitating the behavior of some situation or some process by means of something suitably analogous (especially for the purpose of study or personnel training)
Research method in which information is obtained by asking many individuals a fixed set of questions.
A preference that prevents one from being impartial; prejudice.
In an experiment, a variable, other than the independent variable, that could influence the dependent variable.
The tendency of many human subjects to show a response even when administered a placebo.
An experiment in which neither the experimenter nor the participants know which participants received which treatment.
A process of choosing the members of the experimental and control groups without bias.
Completly Randomized Design
All experimental units have an equal chance of receiving any treatment.
When groups of experimental units with similar charastics are gathered.
Randomized Block Design
Divide subjects with similar characteristics into blocks, and then within each block, randomly assign subjects to treatment groups.
Match pairs of people with traits significant to experiment then randomly put one in treatment and one in control.
The repetition of an experiment in order to test the validity of its conclusion.
A count or measure of the entire population.
A count or measure of part of a population.
The difference between a sample's results and the true result if the entire population had been interviewed.
A sample in which every element in the population has an equal chance of being selected.
Simple Random Sample
A sample of size n selected from the population in such a way that each possible sample of size n has an equal chance of being selected.
A sampling design in which the population is divided into several subpopulations, or strata, and random samples are then drawn from each stratum.
A sample obtained by selecting a preexisting or natural group, called a cluster, and using the members in the cluster for the sample.
A sample in which elements are selected at predetermined intervals.
A sample chosen without any random mechanism; samples chosen based on ease of selection.