PY 211 Lecture Notes - Lecture 8: Community Reinvestment Act, Normal Distribution, Standard Deviation

• School: University of Alabama
• Department: Psychology
• Course: PY 211
• Professor: Beverly B Roskos- Ewoldsen

Document Summary

Frequency polygon of a normal distribution (proportion: describes what it is, can use to estimate probable scores. How does the standard deviation affect the confidence in your estimate: smaller sds, larger sds. Proportions remain the same (68%, 95%, 99. 7%) Normal distribution in behavioral science: measurements of behavior, attitudes, thoughts, form normal distributions (approximately, mean = median = mode. Characteristics of normal distribution: theory, mathematically defined, theoretical, tails are asymptotic (tails never reach 0 frequency, area under curve is 1. 0. Properties: mean, median, mode are all at 50% percentile, symmetrical, mean and standard deviation can have any values (positive values only) Standard normal distribution: transform all x scores to z scores, z = x-m / sd, z-score transformation, z-score distribution (standard normal distribution, mean always translate to a z score of 0. Transformed mean and standard deviation: new mean: m = 0, new sd = 1.