Understanding Score Transformations: Impact on Data Distribution

1. Module 9 Score Transformations and Their Effects • Why transform? • Effects on Central Tendency • Effects on Dispersion • Commonly transformed scores

2. Why do it? • To curve grades! Higher or lower • When they are less or more spread out than origionaly

3. Effect of Transformations on MeanCentral Tendency • Transformations – applying the same adjustment to all scores in a data set • Effects on the mean • Adding or subtracting a constant to all scores will increase or decrease the mean by that constant • Multiplying or dividing all scores by a constant will cause the mean to be multiplied or divided by that score

4. Effect of Transformations on Dispersion • Effects on Dispersion • Adding or subtracting a constant to all scores will not effect measures of dispersion • Multiplying or dividing all scores by a constant will cause measures of dispersion to be multiplied or divided by that score

5. Common Transformations