4. Data Interpretation Drawing Conclusions

Instructions Look at the results from the following five investigations and draw conclusions. Comment on whether or not the result is significant and the strength of the effect. You will need to use critical value tables to do this. Use the 5% significance level throughout. If measures of central tendency and dispersion are quoted, comment on them and also any anomalous results.

Chi-Square Piaget Conservation Experiment Hypothesis: -Seven year olds will be more likely to be able to conserve volume than five year olds. See the next slide for contingency table of raw data. After calculation X2 = 8.64, df = 1, p < 5%

Chi-Square (Continued)   Number able to conserve Number unable to conserve Row total (RT) 5 year olds 8 1 12 2 20 7 year olds 17 3 3 4 Column Totals (CT) 25 15 Grand Total (GT) = 40

Mann Whitney U Test Hypothesis: - Males will score higher on an aggression questionnaire than females. After Calculation U = 47, N1 = 10, N2 = 10 Males Females  Scores on questionnaires 16 14   11 12 4 6 15 9 20 5 13 11.8 Mean 4.54 3.86 Standard Deviation

Wilcoxon Test Top Half of Face 10 Bottom Half of Face Number of faces identified correctly 8   11 4 9 5 8.36 8.54 Mean 2.27 2.65 Standard Deviation Hypothesis: - Participants will be more likely to identify a celebrity from the top half of their face rather than the bottom. After Calculation W = 17.5, N = 10.

Sign Test Participant No: Attitude before film Attitude after film Direction of Influence 1 For Against - 2 3 4 No change 5 6 7 8 9 10 + A study was conducted to discover if students changed their attitude towards the death penalty after watching ‘The Green Mile’.  Experimental Hypothesis: - Watching the film ‘The Green Mile’ will influence student’s attitudes to the death penalty. (non-directional – two-tailed) After calculation S = 1, N = 9 (no change omitted)

Spearman’s Rank Order Correlation Co-efficient Murstein’s Matching Hypothesis of Interpersonal Attraction. Hypothesis: - There will be a positive correlation between attractiveness ratings given to brides and grooms After Calculation rs = 0.689, N = 10. Grooms – Average Ratings Brides – Average Ratings 2 2.5 3.6 6.4 6.5 5.2 5.8 7.3 4.2 5.5 4.5 5.4 4.1 5.3 4.9 6.3 2.8 2.6 Again, worth a summary of key learning points on a last slide?

Calculating Statistics A variety of statistics calculators are available free online, or can be downloaded free from the web. Here are just a few; if you search using an online search engine, we are sure you’ll find more! http://www.brightstat.com/ http://www.graphpad.com/quickcalcs/index.cfm http://statpages.org/ http://statpages.org/javasta2.html#Freebies http://www.physics.csbsju.edu/stats/