Summary of SPSS Menu Bar/SPSS
analyses:
- File
- New à from here you can open a new data
window or syntax window.
- Like every other program you’ve ever
used, you can open, save, and print files. Nothing new here!
- Edit
- Per usual, you can undo and redo
changes, copy and paste, as well as insert variables and cases of
particular variables.
- Option à From this menu, you can alter the
appearance of the data view window, but there is really nothing you
should ever need to change in here.
- View
- Useless. Just use the “Data
View”/“Variable View” tab on the bottom left-hand side of the page.
- Data
- Define
Variable Properties à This dialog window is really another
window to do the same thing as the variable view. Variable view is what you should use
to work with to add labels, change the measurement level (eg: nominal v.
scale), and column widths.
- The rest
of the menu might be used in advanced stats courses (with transposing or
weighing cases), but is overkill for an intro methods course.
- Transform
- Compute
variable à If you ever need
to do any sort of transformation (like a log transformation or translate z-scores into t-scores, this is a handy window. It works much like Calculator on a PC. You simply type in the expression you
want (For example, if you have a z-score
you want transformed into a t-score,
I might input “z_boredom*10+50”
in the “Numeric Expression” window and set the “Target Variable” a new
variable called t_boredom.). We will work more with this later in
the course.
- Recode
into Same/Different Variable
à If for some reason you want to change
the way you coded a variable, congratulations for doing it wrong the
first time. Now you can fix it.
- Analyze
- Reports
- Case
Summaries à This
will allow you to display a table with the raw data grouped by subject
or any other categorical grouping you wish.
- Report
Summaries (in Rows/Columns) à This window will display the mean,
median, standard deviation, skewness, maximum, minimum and many more
statistics in the output window depending on how you want it
presented. You choose which
statistics you want by choosing “Summary…” under the “Report” option.
- Descriptive Statistics
- Frequencies
à Find out how many people answered a particular question
a certain way. (How many males & females are in the sample? How many people answered 7 out of 7
for the “boredom in class” question?)
- Descriptives
à get the N, Minimum, Maximum, Mean and Std. Deviation
with basic descriptives (you can add more in “Options”). Also, by checking the box “Save
standardized values as variables,” you are creating z-scores (standard
scores) for those variables.
- P-P Plots à A probability-probability plot can
be used to see if your data follows some specified distribution. It should be approximately linear if
the specified distribution is the correct model. If not, then a linear transformation
might be in order.
- Q-Q
Plots à A quantile-quantile plot is another method for seeing
if your data follows some specified distribution. Again, if it’s not linear, you’ll
need to transform or use a nonparametric test.
- Compare Means
- Means à Use this option if you just want to
compare means without any statistical mumbo jumbo. But since you love statistical mumbo
jumbo and need to know the statistical mumbo jumbo anyway to do well in
the course, you will instinctively use a real statistical test like a
t-test or ANOVA.
- One-Sample
T-Test à Use this test when you want to see if the mean of your
normally distributed sample is significantly different from a known mean
(usually a population parameter).
You enter this known mean in the “Test Value” field. For example, if you know the average
salary of a grade school teacher is $48,788, use this test to see if the
mean salary of a Northfield teacher is significantly different from the
national average.
- Independent
Samples T-Test à Use this test when you want to compare the means for one
or more variables between two independent groups. You will have to define what your two
groups are by clicking on “Define groups.”
- Paired
Samples T-Test à Use this test when you want to compare the means for one
or more variables between two groups that are not independent. For example, if you wanted to compare
the mean weight loss between males and females from a sample of couples
you could not assume independence of observations.
- One-Way
ANOVA à Use this test when you want to compare the means for a
certain variable between three or more groups assuming a normal
distribution, approximately equal variance, and independence of the
observations in your sample.
- Generalized
Linear Models
- Univariate
à This model is “general” in the sense that one may
implement both regression and ANOVA models. One may also have fixed
factors, random factors, and covariates as predictors.
- In the advanced package of SPSS, you
can also run multivariate generalized linear models as well as
repeated-measures models. If you
need to do these kinds of analyses, learn how to use STATA (free on
campus, but more difficult to use) or be prepared to sell a kidney to
buy the $800 yearly license for the SPSS advanced add-on module (on top
of the $600 dollars you’ve already spent on SPSS Base).
- Correlate
- Bivariate à When one usually thinks of
correlation, this is it. You can
choose between Pearson, Kendall’s tau-b, and Spearman correlation
coefficients. SPSS will give
back a matrix in the output window with either one-tailed or two-tailed
tests of significance.
- Partial à Use this correlation when
correlating two variables while controlling for a third or more
variables. You can use partial
correlations to explore whether your variables are overlapping or
discredit the existence of a particular intervening variable.
- Distances
à Do you want to find out the Euclidean distance, squared
Euclidean distance, Chebychev, block or Minkowski distances? Though not. Read on.
- Regression
- Linear à Perform simple (one predictor
variable) and multiple linear (multiple predictor variables) regressions
using this test.
- Curve
Estimation à This isn’t a “final” test in and of itself. It explores the relationship between
one dependent and one independent variable in terms of linear,
logarithmic, inverse, quadratic, cubic, power, compound, S-curve,
logistic, growth, or exponential based models. You might use this to determine the correct test with
which to analyze the data
- Ordinal
(Logistic) Regression
à Use
this type of regression when your dependent variable is a binary outcome
(or at least non-continuous).
The regression will then measure the probability of a particular
outcome.
- Data Reduction
- Factor
(Analysis) à This analysis is used mainly to develop questionnaires
to ensure that the researcher is measuring the construct they are
attempting to explain or predict.
Save this tidbit of information for grad school in quantitative
psychology.
- Nonparametric Tests
- Chi-Square
Test à Analyzes count data to test the null hypothesis.