PY 211 Study Guide - Midterm Guide: Normal Distribution, Standard Deviation, Sampling Distribution

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

Document Summary

That which falls within 2 sds of the mean is considered normal. 2 sds encompassses 95% of the data. Based off of what staticians decided to (cid:271)e the (cid:862)sta(cid:374)dard"(cid:374)or(cid:373)aal (cid:272)ur(cid:448)e. Each z score specifies the distance or standard deviation of a value from the mean z score off one is 1 sd from the mean. Probabilities of values under a normal distribution equal the probabilities under the standard distribution as the proportion of area under each curve is the same at each sd for all normal distributions. We can use probabilities to convert normal distributions to the standard. Steps to convert a normal distribution to the standard: compute z transformation. Z=1, meaning the value falls within 1 sd above the mean in a standard normal distribution. Represents the proportion of area under the standard normal distribution: Column a lists z scores distribution is symmetrical so proportions are the same for corresponding +/- z scores)