# GGR270H1 Study Guide - Sample Size Determination, Statistical Parameter, Systematic Sampling

## Document Summary

-> most often you don"t know how precise the single sample mean as an estimator (i. e. smaller sample sizes) // place interval around the sample mean, and calculate the probability of. )2 where e is the amount of sampling error the researcher is wiling to tolerate // for data measured in proportions, the formula is . n= ( e )2. +/- 1. 96 standard deviations from the population parameter, and 5% chance that it"s not // can call this the 95% margin of error // calculated as 1. 96* standard error --- 95% margin of error --> 95% Margin of error = 1. 96 (n=50 xbar=980lbs s=105 1. 96 ( = 29. 10lbs) // therefore, we can say with 95% confidence that the sample estimate of 980lbs is within +/- 29lbs of the population parameter. Z values associated with say, 90% confidence level are +/- 1. 65 // 90% confidence. 1. 96, 1. 65, and 2. 33 are important z scores ( check above.