2nd Midterm ( Theoretical questions)

Question 1

What is the number of degree of freedom in case of a correlation t-test, if the sample size is 28? its n-2 (but you count them in pairs)

Answer 1

B) 26

correlation t-test

Degree of freedom= 28-2

Question 2

Pick the correct statement

Answer 2

A) the condition of t-test for one sample is that the variable to be analyzed follows normal distribution.

Question 3

we would like to compare the efficacy of an original drug+a generic one. choose the correct null hypothesis.

Answer 3

A) the efficacy of the generic drug is not significantly different from the original.

Question 4

A test for homogenity is to be continued. which method shall be used?

Answer 4

B) Chi-square test

Question 5

The sample p-value calculated during a wilcoxon test is 0,353. The critical p-value is 5%. Choose the correct statement.

Answer 5

B) The null hypothesis is accepted, ex: there is no significant difference between the values measured before + after the treatment.

0,05 < 0,353

Question 6

We want to test with a t-test whether the 47 patients in the hematology ward have the same red blood cell count as the 47 patients in the contagious ward. what is the number of degrees of freedom?

Answer 6

A) 92

47+47 =94

94-2=92

Question 7

We are studying a numerical, continous variable in two groups having equal number of elements. both groups show normal distribution, the variances can be considered equal. can we use mann-whitney u-test in this case?

Answer 7

B) no, we cannot, we have to use t-test, since the conditions fulfill the requirements for t-test.

–> both groups show normal distribution + mann whitney u-test = if there is no normal distribution

Question 8

What is the number of degree of freedom in case of chi square test for homogenity, if we study whether the distribution of male and female patients in our 8 hospitals is uniform?

Answer 8

A) 7

degree of freedom (chi-square): n-1

8-1 =7

Question 9

Choose the right statement

Answer 9

A) Nullhypothesis is accepted, although it is false.

Null hypothesis accepted, though it doesnt belong there ….

Question 10

What is the right decision, if the the calculated sample p-value is 0,022, and the critical p value is 0,125?

Answer 10

The null hypothesis is rejected

0,125 is the critical p value, or significance level = 12,5%

which is greater then the sample p value 0,022 =2,2%

Question 11

The pain killer effect of asprin + a new drug called “Novanopain”is compared. choose the optimal test method.

Answer 11

A) Mann-Whitney U-test

Question 12

What is the number of degree of freedom in case of a correlation t-test, if the sample size is 14

Answer 12

B) 12

n-2= degree of freedom (correlation t-test)

14-2=12

Question 13

The sample p-value calculated during a wilcoxon test is 0,144. the critical p-value is 5%. choose the correct statement.

Answer 13

D) The null hypothesis is accepted, ex: there is no significant difference between the values measured before and after the treatment.

Question 14

What is the right decision, if the calculated smaple p-value is 0,036, and the critical p-value is 0,1?

Answer 14

A) the null hypothesis is rejected

Question 15

what is the number of degrees of freedom in case of a chi-square test for homogenity, if we study whether the distribution of male and female patients in our 5 hospitals is uniform?

Answer 15

b) 4

degree of freedom (chi-square) = n-1

5-1 =4

Question 16

What is the reason of the fact that most physiological variables are characterized by normal distribution?

Answer 16

D) they are influenced by many independent events, and this, according to the central limit theorem yields normal distribution.

Question 17

The correlation coefficient is close to one if….

Answer 17

A) …the relationship between the variable is linear with positive increment.

Question 18

the sample p-value calculated during a wilcoxon test is 0,283.

the significance level is 5%. choose the correct statement.

Answer 18

c) the null hypothesis is accepted, ex: there is no significant difference between the values measured before and after the treatment.

Question 19

We are executing a two-tailed t-test. choose the possible outcome.

Answer 19

A) t=0 and p=1

Question 20

when is ANOVA applicable?

Answer 20

C) if the samples to be compared are idenpendent and normally distributed.