PSYC 310 Chapter Notes - Chapter 12: Internal Validity, Coefficient Of Determination, Scatter Plot
19 Sep 2018
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The goal: to establish that a relationship exists between variables and describe the nature of the relationship. The relationship between two or more variables can be described based on its direction and strength. There is no manipulation of variables, just measurement. Evaluating relationships for numerical scores and ranks. Scores in each pair are identified as x and y. Data can be presented in a list showing the two scores for each individual. The relationship between variables can be visualized by means of a scatterplot. A line of best fit (regression line) shows the overall trend. The direction (slope) of the correlation indicates the nature of the changes in the variables. The degree of association between two variables us the strength of the correlation, expressed as a correlation coefficient. The correlation strength indicates the quality of the fit of the data around the regression line. Problem: not all relationships are linear even though they can be predictable.
