# STATS 10 Chapter Notes - Chapter 9: Central Limit Theorem, Cherry Blossom, Variance

## Document Summary

Sample mean useful for population mean bc it is accurate and has a large enough sample size so its precise. Sample mean is unbiased when est pop mean. Precision goes up with larger sample, bc sample mean has bigger population. Finishing times of all men runners who ran the cherry blossom ten mile run in 2013. Sample 30 runners and calculate the avg then take the sample and repeat it. Typically how far away is the sample mean from. Each dot= sample so either below or above 10 from 91. Sampling distribution; probability distribution of a statistic, the distribution of all possible sample means from repeated random samples mean of the sampling distribution = population mean it"s a unbiased estimator. Sd of sampling mean is standard error, measures precision of an estimator , how much statistic varies from sample to sample. If you increase the sample mean the standard distribution gets more narrower reflecting a smaller standard of error.