1 / 68

Sampling Variability and Confidence Intervals

2. Lecture Topics. Sampling distribution of a sample meanVariability in the sampling distributionStandard error of the meanStandard error vs. standard deviationConfidence intervals for the a population meanSampling distribution of a sample proportionStandard error for a proportionConfidence i

diamond
Download Presentation

Sampling Variability and Confidence Intervals

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Sampling Variability and Confidence Intervals John McGready Department of Biostatistics, Bloomberg School of Public Health

    2. 2 Lecture Topics Sampling distribution of a sample mean Variability in the sampling distribution Standard error of the mean Standard error vs. standard deviation Confidence intervals for the a population mean Sampling distribution of a sample proportion Standard error for a proportion Confidence intervals for a population proportion

    3. Section A The Random Sampling Behavior of a Sample Mean Across Multiple Random Samples

    4. 4 Random Sample When a sample is randomly selected from a population, it is called a random sample Technically speaking values in a random sample are representative of the distribution of the values in the population sample, regardless of size In a simple random sample, each individual in the population has an equal chance of being chosen for the sample Random sampling helps control systematic bias But even with random sampling, there is still sampling variability or error

    5. 5 Sampling Variability of a Sample Statistic If we repeatedly choose samples from the same population, a statistic (like a sample mean or sample proportion) will take different values in different samples If the statistic does not change much if you repeated the study (you get the similar answers each time), then it is fairly reliable (not a lot of variability) How much variability there is from sample to sample is a measure of precision

    6. 6 Example: Hospital Length of Stay Consider the following data on a population of all patients discharged from a major US teaching hospital in year 2005 Assume the population distribution is given by the following:

More Related