BIOSTATS HW HELP! In a study of post-meningitis and post-encephalitic brain dama

Question

BIOSTATS HW HELP!

In a study of post-meningitis and post-encephalitic brain damage, each of 36 subjects was given a battery of test, providing a composite score of each. Low scores indicted considerable brain damage. The subjects were divided into 3 groups according to type of initial infection and into 3 groups according to time since physical recovery from the illness. (a) Give the null and alternative hypotheses that can be tested. (b) Perform the ANOVA at a 5% significance level, (c) Draw valid conclusions.

Explanation / Answer

(a) Null Hypothesis : H0 : There is no statistically significnat effect on brain damage with variation in years.

ALternative Hypothesis : H1 : There is statistically significnat effect on brain damage with variation in years

Null Hypothesis : H0: There is no statistically significnat effect on brain damage with variation in Post - disease groups and control groups.

ALternative Hypothesis : H1 : There is statistically significnat effect on brain damage with variation in Post - disease groups and control groups.

ALternative Hypothesis : H1 : There is statistically significnat effect on brain damage with variation in years

We now draw some conclusions from the ANOVA table . Since the p-value (crops) = 0.1508 > .05 = , we can’t reject the Factor B (years) null hypothesis, and so conclude (with 95% confidence) that there are no significant differences between the effect on Brain Damage by different years.

Since the p-value (blends) = .000443 < .05 = , we reject the Factor A (Post Disease) null hypothesis, and conclude that the disease and control groups are statisitcally effective.

We also see that the p-value (interactions) = .002 < .05 = , and so conclude there are significant differences in the interaction betweenYears and post disease brain disease.

Anova: Two-Factor With Replication SUMMARY 1-2 Years 3-5 years 7-10 years Total Encephallic Count 4 4 4 12 Sum 286 249 210 745 Average 71.5 62.25 52.5 62.08333 Variance 41.66667 92.91667 171.6667 149.1742 Meningitis Count 4 4 4 12 Sum 328 317 240 885 Average 82 79.25 60 73.75 Variance 33.33333 86.25 186 187.8409 Control Count 4 4 4 12 Sum 287 318 359 964 Average 71.75 79.5 89.75 80.33333 Variance 94.25 63 116.25 133.8788 Total Count 12 12 12 Sum 901 884 809 Average 75.08333 73.66667 67.41667 Variance 72.26515 137.1515 411.5379 ANOVA Source of Variation SS df MS F P-value F crit Disease 2050.056 2 1025.028 10.42009 0.000443 3.354131 Years 399.3889 2 199.6944 2.030026 0.150897 3.354131 Interaction 2124.444 4 531.1111 5.399096 0.002508 2.727765 Within 2656 27 98.37037 Total 7229.889 35

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