Blog : Dissertation Statistics Helper

Using the SPSS Split File Command

When a data file includes a grouping variable, it is possible to use the SPSS Split File command (Data >...

Why Do We Need Both p-Values and Measures of Effect Strength?

I was asked why a measure of effect strength was needed in addition to the p-value associated with a significance test. Wouldn't the p-value...

An SPSS Syntax Trap

Every so often changes are made in SPSS syntax that can catch one by surprise. For instance, a few versions...

SUM(VAR1, VAR2, VAR3…) does not equal (VAR1+VAR2+VAR3…)

One often needs to create new variables by combining old variables. For instance, maybe you've got a 5-item inventory and...

Identifying Cases With Excessive Amounts of Missing Data

It's often recommended that cases with excessive amounts of missing data should be eliminated from the analysis. Assuming that you've...

Un-Besseling the Standard Deviation

I recently worked on a project that requires measuring several aspects of diversity in corporate boards of directors. The measure...

Measuring the Variability of a Nominal Scale Variable

Have you ever needed a measure of variability for a nominal scale variable? I did recently. I needed a way...

Recoding String Variables (words) as Numeric Variables (numbers)

I often get data files from clients who have not discovered yet just how much SPSS hates words! As a...

Merging Data Files

One of my clients had to send me data in waves as it became available. The cases in each incoming...

Statistics First. Data Collection Second!

Do not wait to run your statistics until you've collected your data. ...

When a Correlation is a Difference and a Difference is a Correlation

One common way of categorizing statistics involves putting some of them (like t-tests and ANOVAs) into the "significant difference tests"...

Avoid Collecting Data Using Categories

I work a lot with data that my clients have collected on their own, that is, without the benefit of...

If There’s Any Alternative to MANOVA, Use It!

Some of the best advice I received as a grad student learning multivariate statistics was this: If there's any alternative...

How Many Rating Scale Anchors are Needed?

This time let's talk about the use of odd vs. even numbers of scale points in Likert-type rating scales. I...

Why Are Skewed Distributions Called “Positive” and “Negative?”

I guess my intro stat teacher taught me something because I was surprised to learn that so many people don't...

Reading SPSS Regression Output for Partial and Semi-Partial (“Part”) Correlations

Although the output from many SPSS statistical procedures is rich (sometimes too rich), that output is not always clearly labeled....

Should Multi-Item Inventories Contain Reverse-Worded Items?

One common practice used to control for one form of response bias when collecting rating scale data is to reverse-word...

SPSS “Standarized Residuals” Aren’t Really Standardized!

Every so often I stumble across another SPSS quirk. Recently I was doing some customized partial and semi-partial correlations that...

The Method of Modified z-Scores: “You can get any mean you want with…..” (to the tune of Alice’s Restaurant)

Some years ago, when I wrote my text, Statistics for the Social and Behavioral Sciences: Univariate, Bivariate, and Multivariate , I included...

Calculating Survey Response Time From SurveyMonkey Start and Stop Date/Time Data

As a user of SurveyMonkey, I have been annoyed that that platform does not provide a direct measure of the...