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Ch 9 Introduction to t-stat, Ch 15 Correlation - Coggle Diagram
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Ch 15 Correlation
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The Pearson correlation measures the degree and the direction of the linear relationship between two variables.
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The corresponding correlation for the entire population is identified by the Greek letter rho , which is the Greek equivalent of the letter r.
When there is a perfect linear relationship, every change in the X variable is accompanied by a corresponding change in the Y variable
Sum of products
A measure of the degree of covariability between two variables; the degree to which they vary together.
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The variability of X is measured by computing SS for the X scores and the variability of Y is measured by SS for the Y scores.
Because the Pearson correlation describes the pattern formed by the data points, any factor that does not change the pattern also does not change the correlation.
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A correlation is a numerical value that describes and measures three characteristics of the relationship between X and Y.
The Direction of the Relationship The sign of the correlation, positive or negative, describes the direction of the relationship.
A positive correlation, the two variables tend to change in the same direction: as the value of the X variable increases from one individual to another, the Y variable also tends to increase; when the X variable decreases, the Y variable also decreases.
In a negative correlation, the two variables tend to go in opposite directions. As the X variable increases, the Y variable decreases. That is, it is an inverse relationship.
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Outliers
An outlier is an individual with X and/or Y values that are substantially different (larger or smaller) from the values obtained for the other individuals in the data set.
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A partial correlation measures the relationship between two variables while controlling the influence of a third variable by holding it constant.