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Abstract

In criminal justice research, we are often interested in comparing the means or proportions in two samples of data, either two different groups, the same group across time (before/after), or two related samples (e.g., comparing twins). In this chapter, we will walk through using the independent sample t-test for two sample means, dependent sample t-test for two sample means, or z-test to compare means and proportions in R using data from the National Youth Survey, which is a nationally representative survey of 1725 American adolescents, aged 11–17, to gauge adolescents’ attitudes and behaviors on various topics, including school performance, family life, deviance, drug use, and peer influence.

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References

  • Elliott, D. S. (2008a). National youth survey [United States]: Wave I, 1976 [Data file]. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor]. Retrieved from https://doi.org/10.3886/ICPSR08375.v2.

  • Elliott, D. S. (2008b). National youth survey [United States]: Wave II, 1977 [Data file]. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor]. Retrieved from https://doi.org/10.3886/ICPSR08424.v2.

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Data 11.1

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Key Terms

Dependent sample t -test

A test of statistical significance that is used when two samples are not independent.

Independent sample t -test

A test of statistical significance that examines the difference observed between the means of two unrelated samples.

Test for equality of variance

An F-test used to assess the null hypothesis that the two population variances are equal.

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Wooditch, A., Johnson, N.J., Solymosi, R., Medina Ariza, J., Langton, S. (2021). Comparing Two-Sample Means or Proportions. In: A Beginner’s Guide to Statistics for Criminology and Criminal Justice Using R. Springer, Cham. https://doi.org/10.1007/978-3-030-50625-4_11

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  • DOI: https://doi.org/10.1007/978-3-030-50625-4_11

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  • Publisher Name: Springer, Cham

  • Print ISBN: 978-3-030-50624-7

  • Online ISBN: 978-3-030-50625-4

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