Statistics - Descriptive Statistics

Population

The entire group that is being studied.

Sample

A subset of the population used to represent the whole.

Variable

A factor that can change in an experiment.

Descriptive Statistics

Ways to summarize, organize, and simplify data.

Inferential Statistics

Processes used to make decisions about a population based on sample statistics.

Dependent Variable

The variable that is measured in an experiment.

Independent Variable

The variable that is manipulated to observe its effect on the dependent variable.

Discrete Variable

Categorical variables that can only belong to distinct categories.

Continuous Variable

Variables that can take on an infinite number of values within a range.

Nominal Scale

Different names for each group without a quantitative difference.

Ordinal Scale

Ordered rank with directional differences but without specific size.

Interval Scale

Measurement where the amount between each value is equal, with an arbitrary zero.

Ratio Scale

Measurement where the amount between each value is equal and zero is meaningful.

Mean

The average score of a data set.

Median

The middle score in a data set.

Mode

The score that occurs most frequently in a data set.

Histogram

A graphical representation of the frequency distribution of continuous data.

Scatter Plot

A graph used to compare two continuous variables and examine correlation.

Boxplot

A graphical summary of data showing distribution based on five summary statistics: minimum, first quartile, median, third quartile, and maximum.

Outlier

A data point that differs significantly from other observations.

Frequency

The count of how often something occurs.

Sampling Error

The difference between the sample statistic and the actual population parameter.

Correlation

A measure of the relationship between two variables.