Stats exam 1

Levels of Measurement

Four types: Categorical (nominal and ordinal) and Continuous (interval and ratio).

Nominal Variable

A categorical variable where categories are different and unordered.

Ordinal Variable

A categorical variable where categories are different and have a rank order.

Interval Variable

A continuous variable where categories are different, ordered, and have regular intervals.

Ratio Variable

A continuous variable with categories that are different, ordered, have regular intervals, and a true zero.

Moderation

When a third variable (z) affects the relationship between two variables (x and y).

Mediation

When one variable (x) affects another variable (y) through a third variable (z).

Spuriousness

Occurs when a third variable (z) affects both x and y, making their correlation coincidental.

Sampling

A strategy for observing data when not everything can be observed; involves selecting a subset of the population.

Random Samples

Samples selected in a way that each individual has an equal chance of being chosen.

Population Parameter

A value that describes a characteristic of a population.

Sampling Distribution

The distribution of a statistic (like the mean) obtained from multiple samples of the same size.

Sampling Error

The error due to observing a sample instead of the whole population.

Margin of Error

The range of values above and below the sample statistic in a confidence interval.

Descriptive Statistics

Statistics that summarize and describe the characteristics of a dataset.

Univariate Analysis

Analysis of a single variable.

Bivariate Analysis

Analysis of two variables to determine the relationship between them.

Frequency Distribution

A summary of how often each value occurs in a dataset.

Mean

The average value of a dataset.

Median

The middle value of a dataset when ordered.

Mode

The value that occurs most frequently in a dataset.

Standard Deviation

A measure of the dispersion of a set of data points.

Coefficient of Variation

A standardized measure of dispersion of a probability distribution.

Normal Distribution

A probability distribution that is symmetric about the mean, showing that data near the mean are more frequent.

Central Limit Theorem

States that the sampling distribution of the sample mean approaches a normal distribution as the sample size increases.

Z-Score

A statistical measurement that describes a value's relation to the mean of a group of values.