Fit Distributions Results Dialog Box and Quick Tab

Click OK in the Fit Distributions dialog box to display the Fit Distributions Results dialog box, which contains two tabs: Quick and Save Fit.

Quick Tab

Variables << >>. If more than one variable is selected for the analysis, you can switch between them via the Variables << and >> buttons (or use the adjacent drop-down menu).

Distribution << >>. If more than one distribution is specified for the selected variable, you can switch between them via the Distribution << and >> buttons (or use the adjacent drop-down menu).

Summary statistics. Click the Summary statistics button to create a spreadsheet that contains descriptive statistics (e.g. mean, standard deviation etc.) for the currently selected variable.

Summary graph. Click the Summary graph button to produce a compound graph for the selected variable consisting of a histogram, normal probability plot, box plot, and descriptive statistics.

Distribution summary statistics. Click the Distribution summary statistics button to produce the parameter estimation and goodness of fit tests results for each selected distribution for the currently selected variable.

Empirical CDF plot. Click the Empirical CDF plot button to produce a graph that consists of the empirical CDF, the theoretical CDF of the currently selected distribution, and 95% confidence bands for the sample CDF.

Histogram with fit. Click the Histogram with fit button to produce a histogram with the theoretical density function of the currently selected distribution superimposed over the observed frequencies.

Cumulative histogram. Click the Cumulative histogram button to produce a cumulative histogram with the theoretical cumulative function of the currently selected distribution superimposed over the observed cumulative frequencies.

P-P plot. Click the P-P plot button to produce a P-P plot. In the P-P (probability-probability) plot, the observed cumulative distribution function is plotted against the theoretical cumulative distribution function for the same values. If the selected distribution provides a good fit to the observed data, then all data points will fall onto the diagonal in this plot. See also, Conceptual Overviews - Probability-Probability Plots.

Q-Q plot. Click the Q-Q plot button to produce a Q-Q plot. To produce a Q-Q plot, STATISTICA will first sort the N observed data points into ascending order, so that:

x(1) <=.x(2) <= ... <=.x(n)

These observed values are plotted against one axis of the graph; on the other axis the plot will show:

F-1 ((i-radj )/(n+nadj ))

where i is the rank of the respective observation, radj and nadj are adjustment factors (<= 0.5) and F-1 denotes the inverse of the probability integral for the selected standardized distribution. See also, Conceptual Overviews - Quantile-Quantile Plots.

Box plot. Click the Box plot button to display a box and whisker plot for the selected variable. The box and whisker plot will summarize each variable by three components:

A central circle to indicate the mean; a box to indicate the mean plus/minus the standard deviation; whiskers around the box to indicate the mean plus/minus 1.96*standard deviation (hence, if your data follows the normal distribution, 95% of your data should fall within the whiskers).

The following options are available regardless of which tab is selected.

Run simulation. Click the Run simulation button to display the Simulation Methods dialog where you can simulate random data from the best fitting distributions as specified on the Save Fit tab.  Simulated data can be generated independently for each column, or you can select to preserve the correlation structure between the variables.

Cancel. Click the Cancel button to close the dialog box and return to the Fit Distributions dialog box without performing an analysis.

Options. Click the Options button to display the Options menu.