50 likes | 213 Views
Significance Tests – Different Types. Wilcoxon (Matched Pairs). Design: Repeated Measures Data: Ordinal (or above) Tries to show difference between scores in two different conditions – same participants. Find difference in scores
E N D
Wilcoxon (Matched Pairs) • Design: Repeated Measures • Data: Ordinal (or above) • Tries to show difference between scores in two different conditions – same participants. • Find difference in scores • Rank those differences (ignoring the positive or negative signs) • Separate the ranks for the positive differences from the negative • Find the sum of each list • The smaller of the two sums = “T” • “N” = number of differences,not including zeroes • “T” must be lower than value listed on line on the chart
Mann-Whitney (U Test) • Design: Independent Samples • Data: Ordinal • Comparing two different groups of participants who were studied under different conditions. Comparing values of scores for each group. • List data for each group – compare side by side. • Points: • 1 point for each time score is beaten by score in other group • .5 point for each time score is tied by score in other group • Total points for each group – lower total = “U” • Need to know number of scores (“N”) for each group • Use chart – “U” must be equal to or less than the value listed in the chart. Go to next chart if it is not. Continue until you have a match.
Chi-Square Test (x2) • Design: Independent Samples • Data: Nominal (categories) • Each participant’s response is put into one category. Comparing different participants. • Put data into chart with cells. Actual scores are “Observed”. • Calculate “Expected” : R x C / T • (total of Row X total of Column / total of all) • For each cell: (O – E)2 / E ; total these for all cells = x2 • Calculate Degrees of Freedom : (R-1)(C-1) • Use table to check – must use 2-tailed unless one-row/two-cell • x2 must be equal to or exceed the value in the chart for row to fit
Binomial Sign Test • Design: Repeated Measures • Data: Nominal (Category = worse or better) • Participants each take part in two conditions. Data indicates whether they changed positively or negatively. • Give each participant a “+” , “-” or “0”. • Leaving out zeroes, count the number of the least-occurring sign. This = “S”. • Use chart. “N” = number of signs (not zeroes). • “S” must be equal to or less than value in chart.