Psychology 2800E Lecture Notes - Lecture 10: Diminishing Returns, Confidence Interval, Thought Experiment

• School: Western University
• Department: Psychology
• Course: Psychology 2800E
• Professor: Doug Hazlewood

Document Summary

Sampling (part 2): sample size & sampling error. Involves statistics - (w&m ch 15, p. 387-389) process. When dealing with non-random samples, it is difficult to talk about sample size or sampling error. Part 1: sampling error (and a thought experiment : estimating mean midterm grade from random sample of 10 midterm grades. 120 grades in a hat; with replacement; add and divide by ten for mean; suppose sample mean = 75% Generate more random samples of 10 (with replacement: select 10, put back; select 10 ) S1 = 75%; s2 = 65% s1000 = 73% If we plot these means, we"ll get a sampling distribution (distribution of sample means that are randomly selected from the same population). The means from a normal distribution (bell shaped curve) With large number of samples, the mean of the sampling distribution is the same as the mean of the population.