Exam topics for the oral examination - biostatistics (1st semester)

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Problems Probability 1. If we roll a dice, there are 6 possible outcomes. If X represents the value of the outcome, find the following probabilities: a) P(X=1); b) P(X>1); c) P(1
t Ed aV JS tD decr Equal variances assumed Equal variances not assumed Independent Samples Test Levene's Test f or Equality of Variances t-test for Equality of Means 95% Confidence Interv al of the Mean Std. Error Dif f erence F Sig. t df Sig. (2-tailed) Dif f erence Dif f erence Lower Upper 4.351 .051 1.634 19 .119 5.27273 3.22667 -1.48077 12.02622 1.604 15.591 .129 5.27273 3.28782 -1.71204 12.25749 Based on these results, decide whether the treatment was effective or not. Explain your decision (=0.05). Name of the test…………. Null hypothesis………….. Alternative hypothesis………………….. Assumptions…………….. Result of the test Decision about the variances…………… Test statistic, degrees of freedom, p-value……… Decision……………..Interpretation…………………. 3. In a study examining eating habits of secondary school girls, the body weights were measured in two Hungarian cities, in Szeged and in Debrecen. The results are in the following table: The means were compared using two - sample t-test . What is the null hypothesis of this test .................................................................................... ..................................................................................................................................................... Find the difference in means: ..................................................... The t-value was t=1.502. Find the value of degrees of freedom ............................... The p-value was p=0.136 Is there a significant difference between the two populations mean at 5% level. .................... Correlation 1. Based on 5 pairs of data, The coefficient of correlation is r=0.7. Is this correlation significant at 5% level Null and alternative hypothesis:…………………. t-value of the correlation:......................... Degrees of freedom:................................... Decision (t-value in the table t 3,0.05 =3.182) ………………….. Chi-square tests 1. The following table shows the results of placebo and aspirin in an experiment, with the number of people in each treatment group who did and did not develop thromboses. Decide whether the aspirin had or had not effect on thrombus formation. Developed thrombi Free of thrombi Placebo 10 5 Aspirin 10 20 Find the value of the test statistic, and give your conclusion. (alfa=0.05, 2 table =3.84) Nullhipothesys ……………………Assumption ……………………………… Test statistic: …………………….. Degrees os freedom: …………………… Decision about the significance: …………………..: ……………………….. Interpretation: …………………. 3
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Exam topics for the oral examination - biostatistics (1st semester)

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