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  • 00:03


  • 00:09

    NARRATOR: There are many different typesof people in the world.But as scientists, we cannot help grouping people basedon what makes them similar.The California Psychological Inventory--CPI-- groups people into four personality types, alpha, beta,gamma, and delta.The researchers who developed the CPI showed

  • 00:30

    NARRATOR [continued]: that in the world population, roughly 25% of peopleare alphas, betas, gammas, and deltas.However, they speculated that the four personalitytypes were not equally divided among college students.To test their theory, the researchersgathered 588 college students and identified their four

  • 00:51

    NARRATOR [continued]: personality categories.The researchers found that there weremore alphas and gammas at college than betas and deltas.But how can we test whether the differences in proportionswere real or random?Enter the chi-square statistic.The chi-square statistic is used when we simply count how many

  • 01:11

    NARRATOR [continued]: people are in a group, and we cannot use a t test or F ratiobecause we have not measured the group using a scale.We see that the proportions in the population are 25% each,so we would expect that college students would alsohave proportions of 25% each.But we observe that there are more alphasand betas among college students than gammas and deltas.

  • 01:34

    NARRATOR [continued]: What we observe is different from what we expect.The chi-square test compares the observed valuesto the expected values and calculatesa number called a chi-square value.If the chi-square value is large enough,we reject the null hypothesis.We conclude that the proportions for college studentsis different than world population.

  • 01:56

    NARRATOR [continued]: Like the F ratio, however, we must do a follow-up testto determine which groups are different.

Video Info

Publisher: SAGE Publications, Inc.

Publication Year: 2019

Video Type:Tutorial

Methods: Chi-square test, Hypothesis testing

Keywords: chi-square test; hypothesis testing; Statistical testing: overview

Segment Info

Segment Num.: 1

Persons Discussed:

Events Discussed:



The use of the chi-square test to compare observed values with expected values is clearly explained.

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The use of the chi-square test to compare observed values with expected values is clearly explained.

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