Topic 6: Introduction
to Standard Errors
(Week 6)
Aims
Objectives
To be able to explain what the distribution of a sample mean is and to explain qualitatively how it changes with the size of the sample.
To understand how the precision with which a sample mean estimates a population mean can be quantified by measuring the spread of the distribution of sample means, using a collection of many samples.
To know that the SD of the distribution of sample means is called the Standard Error (SE) and that this is an appropriate measure of precision of the sample mean
To know the correct formula for estimating a standard error from a single sample.
This week there is only one document to be studied and one exercise sheet. You will be studying the issue of how well a sample mean performs as an estimator of the population mean and seeing how this is affected by sample size. You will also study how the standard error quantifies this aspect of a sample mean and how to calculate it.
{note that you will need to
download a Minitab macro for question 3 and another for question 5. To
learn what Minitab macros are, where you should save them and how to use the
macro needed for question 3, click here. You can
obtain the macro for question 3 by right-clicking here
and choosing 'Save Target As...'*. The description of the macro needed
for question 5 is given here and the macro itself can
be obtained by right-clicking here and choosing 'Save
Target As...'.}
* this is what you
do in Internet Explorer - with other browsers choose an equivalent function to
download the file. Also, when the dialogue box for the location for
saving the file comes up, there may be an option 'Save as type'. If the
default is 'Text file', change this to 'All files' before downloading.
Further reading on the topics addressed this week can be found in Bland, sections 1 and 2 of chapter 8