Chapter 2

Qualitative system for categorizing objects or people i.e Female =1, Male = 2

• Allows you to rank people or objects according to the quantity of a characteristic i.e
• Class Rank

Allows ranking on a scale with equal units i.e IQs, GRE scores

Properties of interval scales with a true zero point ie height in inches, weight in pounds

A set of scores

• 1) Mean
• 2) Median
• 3) Mode

• 1) Range
• 2) Variance
• 3) Standard Deviation

Measure of variability in distribution of scores

Used in interpreting scores: square root of variance

mathematical measure of the relationship between two variables:

• range -1.0 to + 1.0
• sign indicates the patter of the relationship
• size indicates the strength of the relationship

graph depicting the relationship between two variables. Each mark in the scatterplot actually represents two scores, an individual's scores on the X and Y variable

• 1) Pearson Product-Moment Correlation
• 2) Spearman Rank-Difference Correlation
• 3) Point-Biserial Correlation
• 4) Biserial Correlation

Both variables continuous and on an Interval or Ratio Scale

both variables on an Ordinal Scale

ONe variable continuous and on Interval/Ratio scale, the other a genuine dichotomy

Both variables continuous and on Interval/Ratio scale, but one is reduced o two categories

• 1) If another type of relationship exists, traditional correlations may underestimate the correlation
• 2) If there is a restriction of range in either variable, the magnitude of the correlation will be reduced

• < .3 Weak
• .3 - .7 Moderate
• > .7 Strong

determined both by the size of the correlation coefficient and the size of the sample

The proportion of variance on one variable that is determined or predicatble from the other variable

The proportion of variance in one variable that is not determined or predicatable from the other variable

• A statistical technique for predicting scores on one variable given a score on another
• Predicts criterion scores based on a perfect linear relationship
• Strong correlations result in accurate predictions; weak correlations resul in less accurate predictions