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Experimental Group Control GroupTime (min) Rank Time (min) Rank 140 4 130 1 147 6 135 2 153 8 138 3 160 10 144 5 165 11 148 7 170 13 155 9 171 14 168 12 193 15 ________________________________________________ (N1=8; R1=81) (N2=7; R2=39) N= Number of participants in each group R= the total when we add all of the ranks together STEP 3: Now use the following formula to find U (U= Hypothetical Data). R=Rank; N=Total Number of Observations U=N1*N2+ N1(N1+1)-R1 Example: U = (8) x (7) + 8*(9) - 81 U= 56 + (8 x 9) - 81 U = 56 + 72 – 81 U= 128 – 81 = 47 U = 47 STEP 4: Go to the Mann-Whitney Chart/Table (on the next page). · U = 47. · Is 47 between the N1 to N2 range of numbers on the chart? · If YES, then reject the NULL Hypothesis. · If NO, then accept the NULL Hypothesis. · 47 is NOT between the N1 to N2 range of numbers on the chart so we must accept the Null hypothesis. · This means that our independent variable (IV) did not make a significant difference in the results (Dependent Variable, DV).
Wilcoxon Signed-Ranks Test · This test is used for the repeated measures design to see if there is a significant difference between the before and after trials of your experiment. · The significance for this test must also be 0.05 (called the Alpha Level for this test). · This test involves finding the “critical Z-score” from a Z-table which is 1.96. · If your Z-score is less than -1.96 or greater than 1.96 then reject the null and accept your alternate hypothesis (H1). · This will mean that your Independent Variable (IV) did make a significant difference.
Step 1: Make a chart showing the scores before and after. Before After 28 12 17 31 36 19 35 14 32 20 33 19 Step 2: Add a 3rd column showing the difference between the before and after scores. You find this difference by subtracting. Date: 2015-01-11; view: 1290
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