PSY 250 Lecture Notes - Lecture 8: Scatter Plot, Covariance, Statistical Inference

• School: University at Buffalo
• Department: Psychology
• Course: PSY 250
• Professor: Boomer Joseph

Document Summary

Descriptive statistics: psychologists want to describe behavior. Describing groups: we describe groups in terms of their measured behaviors, we describe the relationships between variables, no causal inference. Descriptive statistics: measurements that summarize data sets as they are, without comparison. Mean: average, the sum of scores divided by the total number of scores, marginal means, grand mean, tell us a lot, (cid:271)ut they a(cid:396)e(cid:374)"t the whole sto(cid:396)y, we need to know how variable these scores are. Median: the score at which 50% of the scores are below and 50% are above. Note: this is a measure that is affected by the distribution of scores (not their values): how to calculate. Rearrange a set of numbers in order. Ex: 1, 2, 2, 3, 3, 3, 4, 4, 5, 5. If there are two middle numbers, average them and that is the median. Mode: most frequently-occurring number in a set of values. Ex: 10, 11, 20, 16, 14, 10.