Logistic Regression: A Self-learning Text, Third Edition (Statistics in the Health Sciences)

(vip2019) #1
Partition for the Hosmer and Lemeshow Test

mrsa¼1 mrsa¼ 0
Group Total Observed Expected Observed Expected
1 29 1 1.50 28 27.50
2 30 2 2.44 28 27.56
3 29 4 3.01 25 25.99
4 29 5 4.76 24 24.24
5 29 10 7.87 19 21.13
6 29 11 12.96 18 16.04
7 31 17 18.27 14 12.73
8 32 22 21.93 10 10.07
9 31 24 23.85 7 7.15
10 20 18 17.40 2 2.60


Hosmer and Lemeshow Goodness-of-Fit Test

Chi-Square DF Pr>ChiSq
2.3442 8 0.9686


  1. Is the model being fitted a fully parameterized model?
    Explain briefly.

  2. Is the model being fitted a saturated model? Explain
    briefly.

  3. a. Is the deviance value of 157.1050 shown in the
    above output calculated using the deviance formula
    Devðb^Þ¼ 2 lnðL^c=L^maxÞ;
    whereL^c¼ML for current model andL^max¼ML
    for saturated model? Explain briefly.
    b. Why cannot you use this deviance statistic to test
    whether the interaction model provides adequate fit
    to the data? Explain briefly.

  4. a. What can you conclude from the Hosmer–
    Lemeshow statistic provided in the above output
    about whether the interaction model has lack of fit
    to the data? Explain briefly.
    b. Based on the Hosmer–Lemeshow test results for
    both the no-interaction and interaction models,
    can you determine which of these two models is
    the better model? Explain briefly.
    c. How can you use the deviance values from the out-
    put for both the interaction and no-interaction
    models to carry out an LR test that compares these
    two models? In your answer, state the null hypothe-
    sis being tested, the formula for the LR statistic
    using deviances, carry out the computation of the
    LR test and draw a conclusion of which model is
    more appropriate.


Test 341
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