Zach Steiner » Psychology

What is wrong with the Chart Builder in SPSS?

Zach — Sat, 07 Mar 2009 18:33:05 +0000

I am the lab instructor for a graduate psychology statistics course. For my class’s homework, they were required to figure out if a linear regression transformation was warranted for a sample data set. When assessing the skewness of a distribution, scatterplots are invaluable. Unfortunately, SPSS does not render them consistently even within itself. The data set is very skewed and requires natural log transformations for both X and Y to not violate assumptions of linear regression.

Consider first the chart editor, the option SPSS prefers by hiding the “legacy dialogs” inside a submenu. I suspect that eventually these will be altogether removed from the menus, leaving the commands available via syntax for backwards compatibility. The following syntax generated this graph:

GGRAPH /GRAPHDATASET NAME="graphdataset" VARIABLES=BODY BRAIN MISSING=LISTWISE REPORTMISSING=NO /GRAPHSPEC SOURCE=INLINE. BEGIN GPL

SOURCE: s=userSource(id("graphdataset")) DATA: BODY=col(source(s), name("BODY"), unit.category()) DATA: BRAIN=col(source(s), name("BRAIN"), unit.category()) GUIDE: axis(dim(1), label("BODY")) GUIDE: axis(dim(2), label("BRAIN")) ELEMENT: point(position(BODY*BRAIN))

END GPL.

It looks like a linear relationship, right? Wrong! The scale is grossly off. The Body variable actually goes up over 6000. The true relationship is shown through the hidden (supposedly deprecated) legacy dialogs. Which is rendered with much more parsimonious syntax:

GRAPH /SCATTERPLOT(BIVAR)=BODY WITH BRAIN /MISSING=LISTWISE.

Just for yucks, I copied the data in Numbers, a consumer spreadsheet app from Apple. It even does a better job of displaying the data than SPSS’s chart builder.

I am left with a lot of questions and few answers. Why did the chart builder cut off those points at the upper range that radically skew the data set? Why is the syntax for the chart builder 4 times as long as the old charting syntax? Why can’t the chart builder do as accurate a graph as a “baby” spreadsheet app? What is going on here?

Guns versus Gas

Zach — Fri, 23 May 2008 22:33:32 +0000

Why Guns Over Gas?

The answer is not, “Because they are American…” This is consistent with what we know about rewarding people in the workplace. If you offer someone a vacation or a bonus to their paycheck, they will more likely pick the vacation. It’s not something they would regularly pay for on their own and “feels” more like a reward than a bonus, which would likely go toward something mundane like a paying credit card debt or getting ahead on a car/mortgage payment. Offering the choice, though makes the vacation less appealing because of guilt. This gets into the psychology of choice. Interestingly, people tend to prefer less choice to more choice. Research into consumer choice would indicate that Apple’s offering of computers is more optimal than, say, Dell’s. People look more when there is choice, but buy more when there is less choice. For more see Shah & Wolford, 2007 in Psychological Science.

Justice

Zach — Thu, 22 May 2008 00:20:30 +0000

I study organizational justice as part of my research. Organization justice perceptions influence a lot of important outcomes in the workplace. For instance, a worker who feels as if he or she is treated unfairly will likely not be satisfied, committed, or even a productive worker. The notion of justice (and it’s components or types) has been studied by psychologists since at least the 1960s. However, I found recently that the ideas underlying our notions of justice are much older. Aristotle wrote about distributive justice in his Nicomachean Ethics: ”Of particular justice and that which is just in the corresponding sense, (A) one kind is that which is manifested in distributions of honour or money…” (Chapter 2, Book 5). His notion of distributive justice is startlingly similar to the contemporary conceptualization used in psychological research. Essentially, people get angry when their outcomes are not equitable. Following from Adams’s Equity Theory, people want their output (e.g., pay) to be commensurate with their input (e.g., effort). If these are out of of balance, the person will perceive distributive injustice. This is a clarity of the ancient Roman notion of justice from the Justinian code: “…the constant and permanent will to render to each person what is his right.” This is vague from a legal and philosophical stand point, but cast in the light of individual perception, equity theory can be applied. A person’s due (and their right to it) stems from their idea of what they think is an appropriate outcome given what they put in. This seems troublesome given an reliance on individual perception, but psychologists study the individual and the relationships amongst their thoughts, feelings, and behaviors. The objective fairness is immaterial when a person feels slighted, the guy reaction of “That’s not fair!” kicks in; that impulse is precisely what leads to the outcomes that I discussed earlier.

These ideas are not new, per se, but I feel as though there is progress being made. Aristotle did not take about procedural or interactional justice; these are more contemporary discoveries.

More musings to follow on justice as I work through Rapheal’s “Concepts of Justice,” and various book chapters and articles from the psychological literature.