PSY 370 Lecture 7: wrapping up stats and item analysis and test eval
Document Summary
Distance between the lowest value and the highest value: variance. Gives us a better idea of how spread out the data is is it all clustered near the mean: standard deviation. Easier to interpret on the same scale as our mean: in measurement, variance is good! The more variance, the more we are able to see differences among people. Variance ex: find each score"s distance from the mean, square them. This makes the extreme values really big and important: add them up & divide by n. In other words, find the average distance from the mean! That"s the variance: take the square root to put it back on the original scale. In measurement: the shared variance between two variables: ranges from -1 to 1, positive correlation indicates a positive relationship; negative correlation indicates a negative relationship, size of the correlation indicates the strength of the relationship. A correlation of -0. 75 is bigger than a correlation of +0. 50!
