CS130 Lecture 5

SPSS

SPSS is a statistical analysis program that allows:

• Data management in a spreadsheet-like format
• The ability to create graphs and tables
• A broad range of statistical analyses

Goals for this section of the course include:

• Becoming familiar with Statistical Packages and what they can do
• Creating new Datasets
• Importing & exporting Datasets
• Manipulating data in a Dataset
• Basic analysis of data (mainly descriptive statistics)
• Producing professional quality output using Word, Equation Editor, and SPSS results.
• An overview of SPSS's advanced features

Note: This is not a statistics course such as Math 207. We will only concentrate on basic statistical concepts.

Examining the Help utility within SPSS

SPSS has a very nice help utility as part of the application. Let's briefly examine this utility before diving into SPSS.

Creating a Simple Dataset

Let's go to the Tutorial section entitled "Using the Data Editor" and discuss Data View versus Variable View.

Data View: __________________________________________________________

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Variable View: _______________________________________________________

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5.1 Problem

1. Create the variables needed for the following dataset. They will all be numeric for starters.

Note: Variable names must begin with a letter and cannot contain spaces or any illegal characters. Let's use the following convention for variable namnes: 1) the name begins with a letter and 2) the variable can contain letters, numbers, an underscore, or a period.

2. Switch to Data View and look at your variables.
3. Going back to Variable View, change the type of Name to a String and the decimals column is to be 0, 0, 1, 2, 0, 1, 1.
4. In the Values column, create the Value Labels for Brand where 1 = "M&M/Mars", 2 = "Hershey", 3 = "Charms"
5. Enter the data into the correct SPSS cells in the Data View. As you are entering the data into the cells, you will notice that some of the data cannot be entered correctly. You will need to switch to the Variable View to fix these problems.

Summary Statistics

In the tutorial, let's go to "Examining Summary Statistics for Individual Variables"

SPSS contains the following data types:

• Categorical:
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  • Nominal:
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  • Ordinal
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• Scale:
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Question: For the data in Problem 1, what is the type of data for each of the variables:

• Brand: ______________________________________________________
• Name: ______________________________________________________
• ServingPerPkg: _______________________________________________
• OzPerPkg: __________________________________________________
• Calories: ____________________________________________________
• TotalFatInGrams: _____________________________________________
• SatFatInGrams: ______________________________________________

Different summary measures are used for the different data types:

• Categorical Data:
  • Mode is the category with the greatest number of cases
  • Median is the value at which half of the cases fall above and below and works with ordinal data
• Scale Data:
  • Measure of central tendency: mean (arithmetic average), median
  • Measure of dispersion: statistics that measure the amount of variation or spread in the data, i.e. standard deviation, minimum, maximum

5.2 Problem

For the previous problem, do the following:

Go into the "Analyze Menu -> Descriptive Statistics -> Frequencies" and display the appropriate statistics for each of the variables.

Types of Data Analysis

When doing data analysis, we are interested in two types of summaries:

1. Statistical Summaries (e.g. descriptive, hypothesis testing)
2. Visual Summaries (e.g. tables, graphs)

Statistics is sometimes broken up into two different areas:

1. Descriptive Statistics - a situation is described by the statistics by the collection, summarization, organization and presentation of data.
2. Inferential Statistics - where inferences are made from samples of the population (e.g. smokers smoking a pack of cigarettes per day have a higher cholesterol). In this area we get into Hypothesis testing.

5.3 Problem

A paint manufacturer tested two experimental brands of paint over a period of months to determine how long they would last without fading. Here are the results:

• What do the descriptive statistics tell us about the paint with regard to fading?
  • Method #1: One way has two variable columns where the first is BrandA and the second is BrandB. Enter the above data and find the asked for information. Save this file as BrandMethod1.sav.
  • Method #2: The second way has two columns where the first column is a variable called Brand and the second column is called Fading. Create value labels where 1="BrandA" and 2="BrandB". Enter the information and find the asked for information. Save this file as BrandMethod2.sav.

5.4 Problem

1. To make sure we stay fresh with Excel for the final, here's a little problem. Generate 100 random integer numbers (i.e. the numbers do not contain any decimal places) between 1 and 20. Beside each number output "EVEN" or "ODD". Save this file as random.xls.
2. Import this data into SPSS and create a Histogram and Pie Chart of the dataset.