# Chapter 2

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1. Nominal Scales
Qualitative system for categorizing objects or people i.e Female =1, Male = 2
2. Ordinal Scales
• Allows you to rank people or objects according to the quantity of a characteristic i.e
• Class Rank
3. Interval Scales
Allows ranking on a scale with equal units i.e IQs, GRE scores
4. Ratio Scales
Properties of interval scales with a true zero point ie height in inches, weight in pounds
5. Distribution
A set of scores
6. Measures of Central Tendency
• 1) Mean
• 2) Median
• 3) Mode
7. Measures of Variability
• 1) Range
• 2) Variance
• 3) Standard Deviation
8. Variance
9. Variance
Measure of variability in distribution of scores
10. Standard deviation
Used in interpreting scores: square root of variance
11. Correlation Coefficient
mathematical measure of the relationship between two variables:

• range -1.0 to + 1.0
• size indicates the strength of the relationship
12. Scatterplots
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
13. Major Types of Correlations(4)
• 1) Pearson Product-Moment Correlation
• 2) Spearman Rank-Difference Correlation
• 3) Point-Biserial Correlation
• 4) Biserial Correlation
14. Pearson Product-Moment Correlation
Both variables continuous and on an Interval or Ratio Scale
15. Spearman Rank-Difference Correlation:
both variables on an Ordinal Scale
16. Point-Biserial Correlation
ONe variable continuous and on Interval/Ratio scale, the other a genuine dichotomy
17. Biserial Correlation
Both variables continuous and on Interval/Ratio scale, but one is reduced o two categories
18. Factors that effect correlations
• 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
19. Qualitative interpretation of correlations
• < .3 Weak
• .3 - .7 Moderate
• > .7 Strong
20. Statistical Significance of Correlations
determined both by the size of the correlation coefficient and the size of the sample
21. Coefficient of Determiniation(r squared)
The proportion of variance on one variable that is determined or predicatble from the other variable
22. Coefficient of Nondetermination (1 - r squared)
The proportion of variance in one variable that is not determined or predicatable from the other variable
23. Linear Regression
• 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
 Author: aking13 ID: 36068 Card Set: Chapter 2 Updated: 2010-09-20 21:01:49 Tags: Test Measurement Folders: Description: Chapter 2: The Basic Mathematics of Measurement Show Answers: