Chapter 21A | p. 546 Correlation Correlation relationship or association between two variables – Things to Look for: Direction Positive correlation Negative correlation No correlation Linearity Roughly linear No linear trend Strength Strong (positive/negative) Moderate (positive/negative) Weak (positive/negative) Outliers Isolated points which do not follow the main trend of data DISCARD if result of a recording or graphing error KEEP if it’s a genuine piece of data Types of Relationships Presumed relationship sense but does not have a causation factor –makes Cause and effect relationship change in one directly causes change in other – Reverse and effect relationship independent and dependent variable are reversed – Accidental relationship based purely on coincident – Chapter 21B | p. 550 Pearson’s Product-Moment Correlation Coefficient (r) Correlation coefficient (r) measure of how well a linear model fits data – Parts of the “r” SIGN indicates DIRECTION of the correlation SIZE indicates STRENGTH of the correlation
Chapter 21A | p. 546 Correlation Correlation – relationship or association between two variables Things to Look for: Direction Positive correlation Negative correlation No correlation Linearity Roughly linear No linear trend Strength Strong (positive/negative) Moderate (positive/negative) Weak (positive/negative) Outliers Isolated points which do not follow the main trend of data DISCARD if result of a recording or graphing error KEEP if it’s a genuine piece of data Types of Relationships Presumed relationship –makes sense but does not have a causation factor Cause and effect relationship – change in one directly causes change in other Reverse and effect relationship – independent and dependent variable are reversed Accidental relationship – based purely on coincident Chapter 21B | p. 550 Pearson’s Product-Moment Correlation Coefficient (r) Correlation coefficient (r) – measure of how well a linear model fits data Parts of the “r” SIGN indicates DIRECTION of the correlation SIZE indicates STRENGTH of the correlation
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