STAT141 Chapter Notes - Chapter 7: Scatter Plot, Dependent And Independent Variables
Document Summary
Explanatory (independent) variable: explains or causes changes in the response variable (symbol: x) Response (dependent) variable: measures the outcome of a study (symbol: y) Scatterplot: ideal way to picture associations between two quantitative variables. Axis need not to intersect at (0,0) Examining scatterplots: describe overall pattern with form, direction, strength, and striking deviations: form of relationship: linear (points roughly follow straight line) or curved or clusters. Association overall pattern: strength of relationship: strong (observations closest to fitting a line), direction: positive (positive slope) association and negative (negative slope, unusual observations/outliers: watch for any striking deviations from the. Correlation coefficient (r): numerical measurement of strength of the linear relationship between the explanatory and response variables; used to evaluate strength and direction of two numerical variables. Correlation has no units and is a number between -1 and 1. |r| > 0. 8 means a strong correlation between the variables. |r| close to 0 means a weak linear association.
