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Chi Square Distribution quiz #1 Flashcards

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Chi Square Distribution quiz #1
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  • When will a chi-square statistic be equal to zero?
    A chi-square statistic will be zero when the observed values are exactly equal to the expected values for all categories, resulting in no difference between observed and expected frequencies.
  • Why do you need to find two separate critical values when using the chi-square distribution for confidence intervals?
    The chi-square distribution is asymmetric, so the critical values for the left and right tails are not simply negatives of each other. You must look up each value separately using different areas under the curve.
  • What is the range of possible values for the chi-square distribution?
    The chi-square distribution only takes positive values, starting at zero and extending to positive infinity. It cannot be negative.
  • How do you calculate the degrees of freedom for a chi-square confidence interval?
    Degrees of freedom are calculated as n minus 1, where n is the sample size. This is similar to how degrees of freedom are determined for the t distribution.
  • Which area under the curve do you use to find the right critical value in a chi-square table?
    To find the right critical value, you use the area alpha divided by two to the right of the chi-square value. This corresponds to the right tail of the distribution.
  • What area do you use to find the left critical value in a chi-square table?
    For the left critical value, you use the area one minus alpha divided by two to the right of the chi-square value. This ensures you are referencing the correct tail for the asymmetric distribution.
  • How do you determine alpha when constructing a confidence interval using the chi-square distribution?
    Alpha is found by subtracting the confidence level from one. For example, a 95% confidence level gives alpha as 0.05.
  • What is the process for finding the critical value for a given area and degrees of freedom in a chi-square table?
    You locate the desired area in the top row of the table and then move down to the row corresponding to your degrees of freedom. The intersection gives you the critical value.
  • Why can't you use symmetry to find both critical values in the chi-square distribution?
    The chi-square distribution is right-skewed and not symmetric, so the left and right critical values are not mirror images. Each must be found independently using the table.
  • When rounding chi-square critical values, to which decimal place are they typically rounded?
    Chi-square critical values are usually rounded to the nearest hundredth. This provides sufficient precision for most statistical calculations.