We are looking for an expert in statistics!

In April this year SPSSlog.com was started by Mark and Andris. We have started the log to help people who are struggling with SPSS. Currently we get 50-70 visitors each day, from all over the world. In the few months of the existing of SPSSlog.com we have gotten a lot of questions. Very diverse questions, basic questions like “How do I obtain an overall rating score for a number of Likert scale variables?” but also very statistical orientated questions about the many statistical calculations in SPSS.

9 comments October 10th, 2006 andris

Create an overall variable / rating from a number of ratings / variables

This week Cameron send us the following question:

“I am writing about the stereotypes that people hold in regard to public service employees. Participants are required to rate a private, state, federal and local employee on a number of ratings such as efficiency. It is a 7 point Likert scale.

How do I obtain an overall rating score for each participant for each level of employee?”

Cameron, I assume you have already got your data into SPSS. I also assume you have put each score in a different variable and scored every variable with a figure from 1 to 7. To create an overall rating, you can use the Compute function. You can find this under Transform -> Compute.

1 comment September 29th, 2006 andris

How to export your charts in high resolution

We got a question from Lucinda, who wants to publish her results, but has a problem with the resolution of the output. She asked us:

“I have made some interactive line graphs that have been submitted to a scientific journal for publication. The journal editor says that the resolution of the graphs is not high enough to print. Do you know how I can increase the resolution of the graphs?”

You can export your graphs into different file formats:

1. Rightclick your chart (in the Output window)

2. Choose Eport, which gives you the following pop-up screen:

4 comments September 19th, 2006 andris

Error: The attempt to save the data file has failed because the disk is full, an I/O error has occurred, the variable dictionary is invalid, or the task was interrupted.

We received a question from Ilan Shrira, who got an error while saving a file:

I just bought a 120 gigabyte external hard drive, and whenever I try to save an SPSS file
that’s more than 4 gigabyte onto it, it stops and says “Warning #5322, The attempt to save the data file has failed because the disk is full, an I/O error has occurred, the variable dictionary is invalid, or the task was interrupted”

I didn’t have any trouble saving 2 or 3 gigabyte files of the save type. Is is possible that there’s some other kind of glitch in my file.”

9 comments August 23rd, 2006 andris

Linear regression

We get a lot of questions about regression analysis. We have dug into this and decided to write a post about it, so we can help everyone with this.

You do a regression when you assume that a variable is influencing another one, like in the following example: We assume that cars that run on Diesel have higher costs.

To test this assumption, we run a Linear Regression in SPSS. Take the following steps:

- Define your dependent and independent variable. In our example Fuel is the indepent variable and Costs is the dependent one.
- Click Analyze
- Go to Regression and click Linear
- Click “Fuel” into the Independent variable field, and “Costs” into the Dependent variable field.

5 comments August 21st, 2006 andris

SPSS is everywere

(Source: Flickr)

Add comment August 17th, 2006 mark

Recoding with a syntax

This week we got a question from Timo.

Is it possible to use syntax when recoding variables? For example, if I
had a variable that included the following values:

Ladybird
Bluebird
Elm
Butterfly

and I wanted to recode any values that included ‘bird’ into a new value
‘bird’, can I do this with the Recode transformation?

To solve to problem the following syntax is an option:

DATA LIST LIST /var1(A15).
BEGIN DATA
Bluebird
Ladybird
Birdwatcher
Butterfly
Elm
END DATA.

STRING newVar(A15).
DO IF INDEX(UPCASE(var1),”BIRD”) > 0 .
- COMPUTE newVar=”BIRD”.
END IF.
EXECUTE.

Add comment August 17th, 2006 mark

SPSS 15.0 … curious?

If you are curious about the latest developments in SPSS, and want to check out the new - still to become available in store - version of SPSS (15.0), visit this page about the See it in SPSS: free seminar exclusively for SPSS customers. Unfortunately for us, only in the US.

Add comment August 15th, 2006 andris

How to create a cross table

The most easy way to present data in a cross table is to use the table function in SPSS. To do this first go to analyze>tables>basic tables. This opens the following screen.

Now we drag the question “what is your sex?” into down and “SPSS lessons” into across. By clicking statistics we will get the following screen.

To get the amount and the row percentage into the crosstable, we drag “row%” and “count” into the right box. Now we click continue.
By clicking ok you will get the following cross table:

Tip: If you want a total percentage or amount in your table, just click on “total” at the basic tables screen, and choose the option “totals over each group variables”.

4 comments May 27th, 2006 mark

How to create a frequency table

The most easy way to present data is to create a table. There are different ways in SPSS to create a table. We will describe the most common way of creating table.
The most common way of creating a table is with the descriptive statistics function. To do this first go to analyze>descriptive statistics>frequencies. This opens the following screen:

Now we drag the question “what is your sex?” into the variables. By clicking ok you will get the following tables:

The first table shows how many valid cases there are and how many there are missing.
The second table shows:
- The 1st column: This shows the value names and the total.
- The 2nd column: This show the frequency of the values.
- The 3rd column: This shows the percentage of the values including the missing cases.
- The 4th column: This shows the percentage of the values excluding the missing cases.
- The 5th column: This shows the cumulative percentage; this can be important information.

2 comments May 21st, 2006 mark