Chapter 2 - Looking at Data-Relationships

Flashcards covering key vocabulary and concepts from the lecture notes on data relationships, including scatterplots, correlation, regression, and two-way tables.

Explanatory Variable

Explains or causes changes in the response variable.

Response Variable

Measures an outcome of a study.

Scatterplot

A graph that displays the relationship between two quantitative variables measured on the same cases.

Positive Association

When above-average values of one variable tend to accompany above-average values of the other, and below-average values tend to occur together.

Negative Association

When above-average values of one variable tend to accompany below-average values of the other, and vice versa.

Correlation (r)

Measures the strength of the linear relationship between two quantitative variables.

Regression Line

A straight line that describes how a response variable y changes as an explanatory variable x changes. Used to predict the value of y for a given value of x.

Least-Squares Regression Line (LSRL)

The line that minimizes the sum of the squares of the vertical distances of the data points from the line.

Residual

The difference between an observed value of the response variable and the value predicted by the regression line.

Residual Plot

A scatterplot of the regression residuals against the explanatory variable which helps assess the fit of a regression line.

Outlier

An observation that lies outside the overall pattern of the other observations.

Lurking Variable

A variable that is not among the explanatory or response variables and yet may influence the interpretation of relationships among those variables.

Two-Way Table

Describes two categorical variables, organizing counts according to a row variable and a column variable. Each combination of values for these two variables is called a cell.

Marginal Distribution

The distribution of values of that variable among all individuals described by the table.

Conditional Distribution

A conditional distribution of a variable describes the values of that variable among individuals who have a specific value of another variable.

Simpson’s Paradox

An association or comparison that holds for all of several groups can reverse direction when the data are combined to form a single group!