PSY201H5 Lecture Notes - Lecture 5: Statistical Inference, Unimodality, Extraversion And Introversion
Document Summary
: typical amount scores vary/average distance from the mean o. Is the mean trustworthy: low std. Dev. = most scores will be close to average: high std. Dev. = scores will deviate quite a bit from the average. Sat: scores need to be placed on a common scale. Standardization: transforming distributions into a common distribution: convert original scores (x values) into z-scores, z-score: number of standard deviations from the mean a given. X-value was on the original scale: how many sd units the raw score is from the mean o. Shape will be the same as the original distribution. Importance: many variables are normally distributed. Iq, height, weight, extraversion: many inferential statistics are based on assumptions underlying this distribution, we can easily determine how likely an observation is in a normal distribution. Percentage breakdown: only 50% of symmetrical curve: 34. 15%=between mean and +1 std. dev, 13. 59%=between +1 std. dev. And +2 std. dev: 2. 15%=between +2 std. dev.
