Statistics Fundamentals and Hypothesis Testing

A set of flashcards covering key concepts, definitions, and procedures related to statistics and hypothesis testing.

Descriptive Statistics

Used to summarize and describe data from a research study.

Inferential Statistics

Allows researchers to draw conclusions and make inferences about a population based on a sample.

Variable

A characteristic that can have different values, such as stress level.

Value

A number or category that represents a specific characteristic.

Score

A particular person’s value on a variable.

Numeric Variable

Variable whose values  are numbers that tell you how much of something there is. 

Equal-interval Variable

Numbers represent approximately equal amounts of what is being measured. ex) stress level

Rank-order Variable

Values are ranks indicating order but not consistent differences between them.

Nominal Variable

Variable whose values are categories (e.g., gender or religion).

Discrete Variable

Variables with specific values that cannot take on values between them. (college major)

Continuous Variable

Variables that can theoretically take an infinite number of values between any two points.

Histogram

A bar chart showing the pattern of frequencies in a dataset.

Kurtosis

The extent to which a distribution is more peaked or flat compared to a normal curve.

Ceiling Effect

When scores pile up at the high end of a measurement.

Floor Effect

When scores pile up at the low end of a measurement.

Mean (M)

The arithmetic average of a dataset; total scores divided by the number of scores.

Median

The middle score in a dataset when arranged in order.

Mode

The value that occurs most frequently in a dataset.

Variability

A measure of how spread out scores are in relation to the mean.

Variance (SD^2)

The average of each score's squared difference from the mean.

Standard Deviation (SD)

The square root of variance, representing the average amount scores vary from the mean.

Z-Score

Describes a score in terms of how many standard deviations it is above or below the mean.

Normal Curve

A unimodal, symmetrical, bell-shaped distribution commonly found in nature.

Central Limit Theorem

In the long run, random influences combine to create a precise normal curve.

Sample

A smaller part of a population that is studied to make inferences about the whole.

Probability

The expected relative frequency of an outcome.

Hypothesis Testing

A systematic procedure for determining whether study results support a hypothesis.

Significance Level (Alpha)

threshold for deciding if test results are statistically significant

Type I Error

Rejecting the null hypothesis when it is true.

Type II Error

Failing to reject the null hypothesis when it is false.

Statistical Power

The probability that a study will produce a significant result if the research hypothesis is true.