Wilcoxon Matched Pairs Test: Ordinal Data Analysis for Comparing Conditions, Study notes of Psychology

Download Wilcoxon Matched Pairs Test: Ordinal Data Analysis for Comparing Conditions and more Study notes Psychology in PDF only on Docsity! Page 68 Wilcoxon Matched Pairs Signed Rank Test This test is similar to a matched (repeated measures) t-test. However, the dependent variable is measured on an ordinal scale (ranked data). This test is used to test for significant differences between two conditions of an independent variable in an experiment where the same (or matched) participants are responding in both conditions of the study. The dependent variable involves ranked (ordinal) data. Suppose for example, a department chair wanted to find out whether their department faculty members had a significant preference for one job candidate over another. Each of two job candidates (Dr. Smith and Dr. Jones) came to the department for a job interview. After each candidate gave a one hour guest lecture to the members of the department, and after they were interviewed by the members of the department, the faculty in the department were asked to rank order their preferences for the candidates. The first choice of each department member was given a rank of 1 and their second choice a rank of 2. The department chair then recorded the rankings of each candidate by each department member in the table below: Rank Order of Candidates by Faculty Faculty Member Dr. Smith Dr. Jones A 1 2 B 1 2 C 1 2 D 1 2 E 2 1 F 1 2 G 1.5 1.5 H 1 2 I 1 2 J 1 2 1. Logon to system 2. Click Start > Programs > SPSS for Windows > SPSS 10.1 for Windows. At this point a window will appear asking you what you would like to do. Click on the circle next to Type in Data (2nd option in list) and then click OK at the bottom of the window. 3. A Data Editor will appear. Look in the lower left corner of the screen. You should see a Data View tab and to the right of it a Variable View tab. The Variable View tab will be used first for the Data Definition Phase of creating a data file. The Data View tab will be used to actually enter the raw numbers listed above. (See pages 1-3 for a more detailed explanation of creating data files.) DATA DEFINITION PHASE 4. Click on the Variable View tab in the lower left corner. A new screen will appear with the following words at the top of each column. Name Type Width Decimals Label Values Missing Columns Align Measure 5. Click on the white cell in Row 1 under the word Name and type in the word Smith 6. Click on the white cell in Row 1 under the word Label and type in Smith Rank. (Doing this will provide you with a more expansive label in the results output). 7. Click on the white cell in Row 2 under the word Name and type in the word Jones 8. Click on the white cell in Row 2 under the word Label and type in Jones Rank. (Doing this will provide you with a more expansive label in the results output). DATA ENTRY PHASE Page 69 Descriptive Statistics 10 1.1500 .33747 1.00 2.00 10 1.8500 .33747 1.00 2.00 Smith Rank Jones Rank N Mean Std. Deviation Minimum Maximum Ranks 1a 5.00 5.00 8b 5.00 40.00 1c 10 Negative Ranks Positive Ranks Ties Total Jones Rank - Smith Rank N Mean Rank Sum of Ranks Jones Rank < Smith Ranka. Jones Rank > Smith Rankb. Smith Rank = Jones Rankc. 9. Click on the Data View tab in the lower left corner. The data view screen will now appear with Column 1 named Smith and Column 2 named Jones. 10. Enter the data for each of the two candidates as follows. Mouse to the top cell under the first column which is Smith and enter the following: 1 tab 2 1 tab 2 1 tab 2 1 tab 2 2 tab 1 1 tab 2 1.5 tab 1.5 1 tab 2 1 tab 2 1 tab 2 Data Analysis 1. Click on Analyze at top of screen then a. Click on Non-Parametric Tests then b. Click on 2 Related Samples 2 Highlight both Smith and Jones by clicking on them then a. Click on arrow > to transfer both name to the Test Pair(s) List box 3. Click on White square next to Wilcoxon to place a check mark in the box if one is not already there 4. Click on Options button 5. Click on white square next to Descriptives to place a check mark in the box a. Click continue button 6. Click OK. Doing this will result in analysis being conducted. These results are below.