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Data Lab # 4 June 16, 2008

Data Lab # 4 June 16, 2008. Ivan Katchanovski , Ph.D. POL 242Y-Y. Chi-Square Test: Research and Null Hypotheses, Sample, and Weights. Research hypothesis: Men in Canada are more confident in television than women are

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Data Lab # 4 June 16, 2008

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  1. Data Lab # 4June 16, 2008 Ivan Katchanovski, Ph.D. POL 242Y-Y

  2. Chi-Square Test: Research and Null Hypotheses, Sample, and Weights • Research hypothesis: Men in Canada are more confident in television than women are • The null hypothesis: Men and women in Canada have the same confidence in television • Canadian sample of the 2000 World Values Survey (WVS) • Select Canadian respondents from the 2000 WVS dataset • Identify value for Canada (12) in “nation” variable (v2) • Data-Select cases-If: v2=12 • Select Weight: Data-Weight Cases-Weight Cases By: v245

  3. Chi-Square Test: Dependent and Independent Variables • Dependent variable • Confidence in Television (v150) • Check if recoding values and defining missing values needed • Define -4, 8, 9 as missing values • Independent variable: • Sex (v223) • Check if recoding values and defining missing values needed • Define -4, 8, 9 as missing values

  4. SPSS Commands • SPSS Command: • Analyze=Descriptive Statistics-Crosstabs • “Row” box: select dependent variable (Confidence in Television) • “Column” box: select independent variable (Sex) • “Cells” Option: Column percentages • “Statistics” Option: Chi-square • SPSS Output • Check % of cells that have expected count less than 5 • If large %, collapse categories by recoding values

  5. Results • SPSS Output: • Pearson Chi-square: Asymp. Significance p =.317>p=.05 • Statistically insignificant • Accept the null hypothesis • Reject the research hypothesis: • Canadian male and female respondents do not differ significantly in their confidence in television • The gender differences are statistically insignificant

  6. Modified Hypothesis • New research hypothesis: Confidence in television in Canada differs significantly by the level of education • The null hypothesis: Confidence in television in Canada is independent of the level of education • Select new independent variable: • Education (v226) • Check if recoding values and defining missing values needed • Define -4, 98, 99 as missing values

  7. Chi-Square Test: SPSS Command • SPSS Command: • Analyze=Descriptive Statistics-Crosstabs • “Row” box: select dependent variable (Confidence in Television) • “Column” box: select independent variable (Education v226) • “Cells” Option: Column percentages • “Statistics” Option: Chi-square • SPSS Output • Check % of cells that have expected count less than 5 • 16.7% of cells that have expected count less than 5 • Need to collapse categories

  8. Collapsing/Recoding the Independent Variable • Collapse /recode v226 variable into new variable • SPSS recoding command • Transform/Recode into Different Variables • SPSS “Old and New Values”: • Range from 1 to 7 = 0 • Range from 8 to 9 = 1 • Label values of the recoded education variable (renamed as university education): • 0“Less than university” • 1 “University” • Dummy variable: two values (0 and 1)

  9. Results • SPSS Output: • Pearson Chi-square: Asymp. Significance p =.000<p=.001 • Statistically significant • Reject the null hypothesis • Accept the research hypothesis: • Confidence in television in Canada differs significantly by the level of education • The differences are statistically significant at the .001 or .1% level • 35% of the respondents without university education, compared to 27% of the respondents with university education, have quite a lot of confidence in television

  10. Presenting Results Table 1. Confidence in television in Canada by education level, 2000 World Values Survey, %

  11. Independent Samples t Test • Hypothesis testing: Comparison of the sample means of a dependent variable for two groups that differ on an independent variable • Dependent variable: • interval-ratio • ordinal variable treated as interval ratio • Research Hypothesis: Men have lower level of confidence in television compared to women in Japan • Null hypothesis: Men and women in Japan have the same level of confidence in television

  12. Independent Samples T-test: Dependent and Independent Variables • Dependent variable: Confidence in television (v150) • Ordinal but can be treated as interval-ratio: • If defined as a measure of non-confidence in television because increase in its values means decrease in confidence in television • If recoded by assigning higher values to higher confidence levels • Independent variable: Sex • Two categories (groups): Male and Female • Sampling distribution: Student t distribution • SPSS selects t distribution automatically

  13. Independent Samples T-test: SPSS Commands • Select Japan sample in the 2000 WVS dataset • Identify value for Japan (13) in “nation” variable (v2) • Data-Select cases-If: v2=13 • Check if weights should be used • SPSS Command: • Analyze-Compare Means-Independent Samples T Test • Select Confidence in television (v150) as “Test Variable” • Select Sex as “Grouping Variable” • Define Groups: “Use specified values”: • 1 (Male) and 2 (Female)

  14. Results • Compare means of the dependent variable • Men have higher mean level of non-confidence in television compared to women in Japan: 2.33>2.19 • Select “equal variances assumed” if Leven’s test for equality of variances is statistically insignificant: • Sig.=p=.000>.05 • Select “equal variances not assumed” if Leven’s test for equality of variances is statistically significant: • Sig.=p<.05 • Determine significance in t-test for equality of means • p =.000<p=.001 • Statistically significant

  15. Interpretation of Results • Reject the null hypothesis • Accept the research hypothesis: • Men have lower level of confidence in television compared to women in Japan • The differences are statistically significant at the .001 or .1% level

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