Class KruskalWallisGUI

java.lang.Object

java.awt.Component

java.awt.Container

java.awt.Window

java.awt.Frame

javax.swing.JFrame

KruskalWallisGUI

All Implemented Interfaces:

java.awt.event.ActionListener, java.awt.event.FocusListener, java.awt.event.ItemListener, java.awt.image.ImageObserver, java.awt.MenuContainer, java.io.Serializable, java.util.EventListener, javax.accessibility.Accessible, javax.swing.RootPaneContainer, javax.swing.WindowConstants

public class KruskalWallisGUI
extends javax.swing.JFrame
implements java.awt.event.ActionListener, java.awt.event.FocusListener, java.awt.event.ItemListener

KruskalWallis - GUI Version

Summary

• A utility to perform a Kruskal-Wallis test on a table of data

Background

The Kruskal-Wallis test is a non-parametric statistical procedure to assess the difference between three or more independent samples, which is to say, between three or more conditions assigned between-subjects. The relationship with other non-parametric tests is illustrated below:

Design	Conditions (samples)
	2	3 or more
Between-subjects (independent samples)	Mann-Whitney U	Kruskal Wallis
Within-subjects (correlated samples)	Wilcoxon Signed-Rank	Friedman

The test operates on ordinal data, such as rankings, assessments, or questionnaire responses (where the responses are non-linear). Using the Kruskal Wallis test (or other non-parametric tests) for interval or ratio data over a parametric ANOVA is an option if there is a concern over the underlying assumptions in the distribution of the data. The researcher must bear in mind, however, that the data transformation bears a cost: Information is sacrificed. For example, interval or ratio scores of 80, 79, and 49 are converted to ranks 1, 2, and 3. Yes, information is sacrificed.

The null hypothesis is that the populations from which the samples originate have the same median. A statistically significant outcome implies that at least one of the samples (i.e., conditions) is significantly different from at least one other sample. To determine which pairs of samples differ significantly from one another, a post hoc pairwise comparisons test is performed (see below).

Launch KruskalWallisGUI from GoStats as follows:

Example 1

Consider an experiment to test whether age is a factor in the acceptance of a new GPS navigator system for a car. Eight participants are recruited from each of three age groups (20-29, 30-39, 40-49). The participants are given a demo of a new GPS navigator, then asked if they liked it enough to purchase it for personal use. They respond on a scale from 1 (definitely no) to 10 (definitely yes). The responses are in the GoStatsExamples folder in a file named kruskalwallis-ex1.txt. The data are organized as a table with 8 rows and 3 columns:

 
      9   7   4
      9   3   5
      4   5   5
      9   3   2
      6   2   2
      3   1   1
      8   4   2
      9   7   2
 

The means (not shown) are 7.125, 4.000, and 2.875, for the 20-29, 30-39, and 40-49 year age groups, respectively. Evidently, the participants in the 20-29 year age group liked the GPS system quite a bit, the 40-49 year participants not so much. But, are the differences between age groups statistically significant or are they perhaps just due to chance? To determine this, the Kruskal-Wallis test is performed as follows:

The test statistic (H) follows the chi-square distribution with k - 1 degrees for freedom (k = number of conditions). Since p is below the customary threshold for significance (.05), we reject the null hypothesis. The conclusion is that age is a factor in acceptance of the new design for a GPS navigator.

The test also provides H' which is corrected for ties. The difference is usually minor.

StatView provides the following output using the data above:

Post Hoc Comparisons

If the test reveals statistical significance (as above), post hoc pairwise comparisons are needed to determine which conditions (samples) differ significantly from one another. This is available using the output option "Post hoc tests":

The test reveals that only the samples in columns 1 and 3 are significantly different, corresponding to the responses for the 20-29 and 40-49 year age groups, respectively. The verbose output provides a rough verification of this, as it shows the means by age group (column) cited earlier:

The multiple comparisons test uses the procedure given by Siegel and Castellan in "Nonparametric Statistics for the Behavioral Sciences" (McGraw-Hill, 1988, pp. 213-214; described in a posting on www.talkstats.com).

Example 2 (missing data)

An additional feature of KruskalWallisGUI is accommodation for missing data. If the sample sizes (number of participants) differ among the conditions, substitute a period (".") for missing data. An example is found in kruskalwallis-ex2.txt:

 6.4   2.5   1.3
 6.8   3.7   4.1
 7.2   4.9   4.9
 8.3   5.4   5.2
 8.4   5.9   5.5
 9.1   8.1   8.2
 9.4   8.2   .
 9.7   .     .

Here's the analysis:

The example above contains scores from a study on wine tasting (see http://vassarstats.net/textbook/ch14a.html).

Author:

Scott MacKenzie, 2012-2023

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.awt.Window

java.awt.Window.Type

Nested classes/interfaces inherited from class java.awt.Component

java.awt.Component.BaselineResizeBehavior

Field Summary

Fields inherited from class javax.swing.JFrame

EXIT_ON_CLOSE

Fields inherited from class java.awt.Frame

CROSSHAIR_CURSOR, DEFAULT_CURSOR, E_RESIZE_CURSOR, HAND_CURSOR, ICONIFIED, MAXIMIZED_BOTH, MAXIMIZED_HORIZ, MAXIMIZED_VERT, MOVE_CURSOR, N_RESIZE_CURSOR, NE_RESIZE_CURSOR, NORMAL, NW_RESIZE_CURSOR, S_RESIZE_CURSOR, SE_RESIZE_CURSOR, SW_RESIZE_CURSOR, TEXT_CURSOR, W_RESIZE_CURSOR, WAIT_CURSOR

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Fields inherited from interface javax.swing.WindowConstants

DISPOSE_ON_CLOSE, DO_NOTHING_ON_CLOSE, HIDE_ON_CLOSE

Fields inherited from interface java.awt.image.ImageObserver

ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Method Summary

Modifier and Type	Method and Description
void	actionPerformed(java.awt.event.ActionEvent ae)
void	focusGained(java.awt.event.FocusEvent fe)
void	focusLost(java.awt.event.FocusEvent fe)
void	itemStateChanged(java.awt.event.ItemEvent ie)

Methods inherited from class javax.swing.JFrame

getAccessibleContext, getContentPane, getDefaultCloseOperation, getGlassPane, getGraphics, getJMenuBar, getLayeredPane, getRootPane, getTransferHandler, isDefaultLookAndFeelDecorated, remove, repaint, setContentPane, setDefaultCloseOperation, setDefaultLookAndFeelDecorated, setGlassPane, setIconImage, setJMenuBar, setLayeredPane, setLayout, setTransferHandler, update

Methods inherited from class java.awt.Frame

addNotify, getCursorType, getExtendedState, getFrames, getIconImage, getMaximizedBounds, getMenuBar, getState, getTitle, isResizable, isUndecorated, remove, removeNotify, setBackground, setCursor, setExtendedState, setMaximizedBounds, setMenuBar, setOpacity, setResizable, setShape, setState, setTitle, setUndecorated

Methods inherited from class java.awt.Window

addPropertyChangeListener, addPropertyChangeListener, addWindowFocusListener, addWindowListener, addWindowStateListener, applyResourceBundle, applyResourceBundle, createBufferStrategy, createBufferStrategy, dispose, getBackground, getBufferStrategy, getFocusableWindowState, getFocusCycleRootAncestor, getFocusOwner, getFocusTraversalKeys, getIconImages, getInputContext, getListeners, getLocale, getModalExclusionType, getMostRecentFocusOwner, getOpacity, getOwnedWindows, getOwner, getOwnerlessWindows, getShape, getToolkit, getType, getWarningString, getWindowFocusListeners, getWindowListeners, getWindows, getWindowStateListeners, hide, isActive, isAlwaysOnTop, isAlwaysOnTopSupported, isAutoRequestFocus, isFocusableWindow, isFocusCycleRoot, isFocused, isLocationByPlatform, isOpaque, isShowing, isValidateRoot, pack, paint, postEvent, removeWindowFocusListener, removeWindowListener, removeWindowStateListener, reshape, setAlwaysOnTop, setAutoRequestFocus, setBounds, setBounds, setCursor, setFocusableWindowState, setFocusCycleRoot, setIconImages, setLocation, setLocation, setLocationByPlatform, setLocationRelativeTo, setMinimumSize, setModalExclusionType, setSize, setSize, setType, setVisible, show, toBack, toFront

Methods inherited from class java.awt.Container

add, add, add, add, add, addContainerListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getAlignmentX, getAlignmentY, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getComponentZOrder, getContainerListeners, getFocusTraversalPolicy, getInsets, getLayout, getMaximumSize, getMinimumSize, getMousePosition, getPreferredSize, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusTraversalPolicyProvider, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paintComponents, preferredSize, print, printComponents, remove, removeAll, removeContainerListener, setComponentZOrder, setFocusTraversalKeys, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, setFont, transferFocusDownCycle, validate

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, bounds, checkImage, checkImage, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, disable, dispatchEvent, enable, enable, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getBaseline, getBaselineResizeBehavior, getBounds, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocation, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, imageUpdate, inside, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isPreferredSizeSet, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, prepareImage, prepareImage, printAll, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, requestFocus, requestFocusInWindow, resize, resize, revalidate, setComponentOrientation, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeysEnabled, setForeground, setIgnoreRepaint, setLocale, setMaximumSize, setName, setPreferredSize, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.awt.MenuContainer

getFont, postEvent

Method Detail

actionPerformed

public void actionPerformed(java.awt.event.ActionEvent ae)

Specified by:

actionPerformed in interface java.awt.event.ActionListener

focusGained

public void focusGained(java.awt.event.FocusEvent fe)

Specified by:

focusGained in interface java.awt.event.FocusListener

focusLost

public void focusLost(java.awt.event.FocusEvent fe)

Specified by:

focusLost in interface java.awt.event.FocusListener

itemStateChanged

public void itemStateChanged(java.awt.event.ItemEvent ie)

Specified by:

itemStateChanged in interface java.awt.event.ItemListener