Class MannWhitneyUGUI

java.lang.Object

java.awt.Component

java.awt.Container

java.awt.Window

java.awt.Frame

javax.swing.JFrame

MannWhitneyUGUI

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 MannWhitneyUGUI
extends javax.swing.JFrame
implements java.awt.event.ActionListener, java.awt.event.FocusListener, java.awt.event.ItemListener

MannWhitneyU - GUI Version

Summary

• A utility to perform a Mann-Whitney U test on a table of data

Background

The Mann-Whitney U test is a non-parametric statistical procedure to assess the difference between two independent samples, which is to say, between two 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 Mann-Whitney U 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.

Launch MannWhitneyUGUI from GoStats as follows:

Example 1

Consider an experiment seeking to determine if there is a difference in the political leaning of MAC users vs. PC users. Are MAC or PC users more likely to have political views leaning to the "left" or "right"? The experimenter randomly selects 10 MAC users and 10 PC users. The participants are interviewed and asked a variety of questions about their political leaning. Each participant is assessed on a scale from 1 (very left) to 10 (very right) with the results stored in a text file as a table with two columns. The first column contains the assessments for the MAC users, the second column for the PC users (see mannwhitneyu-ex1.txt in the GoStatsExamples folder):

 
      2   4
      3   6
      2   5
      4   4
      9   8
      2   3
      5   4
      3   2
      4   4
      3   5
 

The means (not shown) are 3.7 for the MAC users and 4.5 for the PC users. Evidently, the PC users are more right-leaning in their political views than the MAC users. But, is the difference of statistical significance or is it likely a chance outcome? To determine this, the MannWhitney test is performed:

For convenience, the test statistic U is converted to a z-score. This facilitates computing p. Since the customary threshold for statistical significance (p < .05) was not observed, the null hypothesis remains tenable, inferring a likelihood that the two samples are from the same population. We conclude there is no difference in the political leaning of MAC users vs. PC users.

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

StatView provides the following output using the data above:

Example 2 (missing data)

Since the design is between-subjects, it is sometimes difficult to have equal-size groups. For example, if two of the MAC participants do not show up for the interview, then there will be 8 participants in the MAC group and 10 participants in the PC group. This is accommodated by using periods (".") for missing data (see mannwhitneyu-ex2.txt):

 2   4
 3   6
 2   5
 4   4
 9   8
 2   3
 5   4
 3   2
 .   4
 .   5

Here's the analysis:

The conclusion is the same. Note that "equal sample sizes" is one assumption of the parametric ANOVA that, if violated, justifies using a non-parametric test, such as the Mann-Whitney U.

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)
static double	getP1()
static double	getP2()
static double[]	getRanks(double[] d)
static double	getU()
static double	getZ1()
static double	getZ2()
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

getU

public static double getU()

getZ1

public static double getZ1()

getZ2

public static double getZ2()

getP1

public static double getP1()

getP2

public static double getP2()

getRanks

public static double[] getRanks(double[] d)