For the most commonly used descriptive measures, select

Stat>Basic Statistics>Descriptive statistics.With the cursor in the "Variables" box, select the columns you want described (highlight them and click on " Select " - or simply double-click on them) and click on OK (or press the Return/Enter key).The printout gives, for each variable:

Variablethe name of the variable (unless you didn't name it - then you get the column number)

Nthe number of values in the column

medianthe "middle" value (half the values are at or above, half are at or below)

meanthe arithmetic mean (x-bar) of the values

TrMeanthe 5% trimmed mean - the mean with the largest 5% and smallest 5% of the values deleted

StDevthe standard deviation (s) of the values

SEMeanthe standard error of the mean - the standard deviation divided by the square root of N

Minthe smallest value in the list

Maxthe largest value in the list

Q1the first quartile - value separating the smallest quarter of the values from the rest

Q3the third quartile - value separating the smallest three-quarters of the values from the rest

Grouped frequency distribution: UseGraph>Character Graphs>Histogram. Select the variable(s) by double-clicking in the list. TheIntervalis the class width (class interval, range for the class), theFirst midpointis the class midpoint of the first class. The resulting printout shows class midpoints (no class limits) and frequencies. [For an actual histogram, which will appear in a separate graph window, use theGraph>Histogramcommand - see IV. Graphs for details.]

Stemplot:UseGraph>Stem-and-Leaf. Select the variable(s) by double-clicking in the list at the left of the window. You can set theincrementat 5 to get a split stemplot. In the display, an extra column at the left of the display shows the "depth" of the class - the distance (number of items) from thenearerend (large or small) of the data. The row with the median is marked in parentheses.This is really a character graph - it shows up in the Session window - it's on the main graph menu because people use it a lot.

Listingthe data in the session window is accomplished with theFile>Display datacommand (select the column or columns you want displayed) - useful if you want a complete list of the values of one variable without printing the whole data window.

Correlation coefficient (Pearson's r): UseStat>Basic Statistics>Correlation....Select the variables for which you want the correlation. If you select more than two variables, you will geat a table giving the correlations between all pairs of variables.

Regression line and coefficient of determination (r-square):UseStat>Regression>Regression. For the "response" select the variable to be the "y" variable (predicted by the eauation) and for the "predictor" use your "x" variable (used to predict the response). The result gives the regression equation and the coefficient of determination (r-squared - labeled "R-sq") and further information - notably pairs with large residuals (potential outliers) and values whose x-values are ver different (influential points) - used for analysis of the equation.

The commandStat>Regression>Fitted line plotwill produce the same output in the session window plus a scatterplot with the rgression line graphed on it.

For graphs, see IV. Graphs

Last update 8/10/00

*Maintained by cpeltier@saintmarys.edu*