# PSYC 307 Chapter 12: PSYC 217 Chapter 12

## Document Summary

Different ways to report central tendency and variability of a data set. Mean- the sum of all the sores divided by the number of scores. Median- the one in the middle from least to greatest sometimes it is better to select median instead of mean if there are extreme outliers. Ordinal scale- rank order of scores taken into account. Correlations: describes association btw 2 variables r > 4 strong r=3 moderate r<3 weak. Pearsons r- determines the direction and strength of the relationship rsquared2- how much shared variability there is between two variables percentage form. Effect size- cohens d - describes strength of relationship between variables difference between groups in sd units. Samples are drawn from a population in order to establish inferences of the population. The larger the sample the more representative of the population- probabilistic trend. Small samples can often be unrepresentative of the population. Gamblers fallacy we see links between events that are independent.