Research Methods 2

Topic 3: Descriptive Statistics (Week 3)

Aims

To introduce the idea of summarising data either by using appropriate statistics or graphs.

Objectives

To be able to calculate and interpret the median and quartiles of a sample of data

To be able to draw a boxplot and histogram of the sample.

To be able to compute and interpret the mean and standard deviation of a sample.

Note: you will need to use Minitab to perform the calculations set in the exercises this week. This will help you to consolidate the skills you learnt last week in Introduction to Minitab.

The first part of the work this week is to do with using numbers to summarise data and comprises the following.

Study the document Data Description: using numerical summaries, which explains why data often need to be summarised and how this can be done.
Answer the questions in Exercise Sheet 1. For this you will need to use Minitab and you may need to refer back to any notes you made last week on getting started with Minitab. You will also need the Minitab Worksheet.*
You should check your answers by referring to the Solutions to Exercise Sheet 1.

When you have done this you should turn to graphical summaries of data, as follows.

Study the document Data Description: using graphs.
Answer the questions in Exercise Sheet 2.
Again, check you answers, using Solutions to Exercise Sheet 2.

Further reading on the topics addressed this week can be found in Bland, sections 4.4-4.7.

There is no formal assessment this week.

* To download the Minitab worksheet right-click the 'Minitab Worksheet' link above and choose '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, make sure you remember where you save the file! The file needs to be saved with a .mtw extension (or as it says in the dialogue box as a .mtw Document): do not worry too much about this bit - it should happen automatically. How to get a Minitab worksheet into Minitab was covered in week 2.