Multiple Choice Questions

Question 1

Linear regression…

.. compares the standard deviation of two variables with the equation of the line
.. characterizes the goodness of the parameters of a fitted line
.. gives the parameters of the line best fitting to the data
.. gives the equation and parameters of the best fitting function

Answer 1

gives the parameters of the line best fitting to the data

Question 2

What is our conclusion if we obtain p =3,5 in a two sample t-test?

.. We accept the null hypothesis
.. Nothing, we do the calculation again
.. Since p>1, there is no significant difference
.. We reject the null hypothesis considering 5% level of significance

Answer 2

Nothing, we do the calculation again

Question 3

When should the Kruskall-Wallis-test be used?

.. If we have more than two independent, numerical samples, some or all of which is not normally distributed
.. if we have more than two independent, numerical, normally distributed samples
.. if we have more than two dependent, numerical, normally distributed samples
.. if we have more than two dependent, numerical samples, some of which are nor normally distributed

Answer 3

If we have more than two independent, numerical samples, some or all of which is not normally distributed

Question 4

In a one-sample t-test the calculated t value is 1.897 and the t value that belongs to the significance level is 2.013. What is your conclusion?

• I repeat my calculation, because this situation can not happen in one-sample t-test.
• I accept the nullhypothesis.
• I reject the nullhypothesis.
• I can not say anything without knowing the probabilities.

Answer 4

I accept the nullhypothesis.

Question 5

What is your conclusion when the calculated p-value of an F-test is higher than the significance level?

.. I have to use Mann-Whitney U-test.
.. Variances are equal.
.. Variances are not equal.
.. I can accept the nullhypothesis of two-sample t-test.

Answer 5

Variances are equal.

Question 6

Simply increasing the sample size would not change the number of degrees of freedom …

… in case of the t-test for two independent samples (supposing unequal variances)
… in case of the chi squared test.
… in case of the F test.
… in case of the t-test for two independent samples (supposing equal variances)

Answer 6

in case of the chi squared test.

Question 7

We are executing a two-tailed F-test. Choose the possible outcome.

.. F = 0 and p = 1.
.. F = 100 and p = 1.
.. F = 1 and p = 1.
.. F = –1 and p = 1.

Answer 7

F = 1 and p = 1.

Question 8

I wanted to use a two sample t-test, but it turned out that the measured variable does not follow normal distriubtion. What test can I use?

.. Wilcoxon test
.. Mann–Whitney U-test.
.. one sample t-test
.. F-test

Answer 8

Mann–Whitney U-test.

Question 9

The correlation correlation coefficient is close to one if …

… the relationship between the variables is linear with positive increment.
… the relationship between the varialbes is function-like.
… the relationship between the variables is linear.
… the relationship between the variables is not significant.

Answer 9

the relationship between the variables is linear with positive increment.

Question 10

The absolute value of the correlation coefficient …

… is the square of the covariance.
… cannot be zero.
… is the square root of the determination coefficient.
… is the maximum value of the alpha error of the correlation t-test.

Answer 10

is the square root of the determination coefficient

Question 11

Linear regression …

… characterizes the goodness of the parmeters of a fitted line.
… compares the standard deviation of two variables with the equation of the line.
… gives the parameters of the line best fitting to the data.
… gives the equation and parameters of the best fitting function.

Answer 11

gives the parameters of the line best fitting to the data.

Question 12

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

.. They are all related to each other so they must have the same (or at least similar) distribution.
.. In fact, most of them does not follow normal distribution, and we rather deal with those few which do.
.. They are actually transformed so that they would follow normal distribution which makes them easier to be dealt with.
.. They influenced by many independent events, and this, according to the central limit theorem, yields normal distribution.

Answer 12

They influenced by many independent events, and this, according to the central limit theorem, yields normal distribution.

Question 13

In meteorology, the intensity of UV-B radiation is classiefied as follows: weak, moderate, strong, very strong, extreme. What is the type of this data?

.. Not enough information to decide.
.. Exponential.
.. Discrete numerical.
.. Categorial.

Answer 13

Categorial

Question 14

Choose the right statement on type II error.

.. Gives the error of wrong decision.
.. Gives the error of the right decision.
.. The null hypothesis is accepted, although it is false.
.. The alternative hypothesis is accepted, although it is false.

Answer 14

The null hypothesis is accepted, although it is false

Question 15

The probability of event ‘A’ is 0.71. What is the maximum possible probability of event ‘B’ if events ‘A’ and ‘B’ cannot happen at once?

.. Exactly -0.71.
.. It can be anywhere between 0 and 1.
.. It can be anywhere between 0 and 0.29.
.. Precisely 29%

Answer 15

Precisely 29%

Question 16

Which of the following values cannot be negative?

.. The Z-value in a Mann–Whitney U-test.
.. The correlation coefficient.
.. The t-value in a paired t-test.
.. The F-value in an F-test.

Answer 16

The F-value in an F-test.

Question 17

A test for homogenity is to be conducted. Which method shall be used?

.. Student’s t-test for two samples.
.. Chi-square test.
.. Student’s t-test for one sample.
.. Mann–Whitney U-test.

Answer 17

Chi-square test.

Question 18

In which case should one reject the null hypothesis?

.. If the absolute value of the statistical parameter calculated from the sample is greater than 5%.
.. If the p-value calculated from the sample is greater than 5%.
.. If the p-value calculated from the sample is greater than the critical p-value.
.. If the absolute value of the statistical parameter calculated form the sample is greater than the absolute value of the critical statistical parameter.

Answer 18

If the absolute value of the statistical parameter calculated form the sample is greater than the absolute value of the critical statistical parameter.

Question 19

What distribution do the data sets follow if we used Wilcoxon test to compare them?

.. Normal distribution.
.. Can be anything different from standard normal distribution.
.. It has a t-distribution with number of dergrees of freedom equal to one minus the sample count.
.. The distribution is either unknown or non-normal.

Answer 19

The distribution is either unknown or non-normal.

Question 20

We are executing a two-tailed F-test. Choose the possible outcome.

F = –1 and p = 1.
F = 1 and p = 1.
F = 0 and p = 1.
F = 100 and p = 1.

Answer 20

F = 1 and p = 1.

NB! T test: t = 0, P = 1

Question 21

We tossed a fair coin 5 times and the outcome was always heads. What is the probability that the outcome of the 6th toss is heads?

.. It is (1/2) ÷ 6 = 1/12.
.. Not enough data to tell.
.. It is (1/2)^6 = 1/64.
.. It is 50%.

Answer 21

It is 50%

Question 22

The consequence of the law of large numbers is …

… that the standard error of a sample goes to the standard deviation of the corresponding theoretical distribution if the sample size goes to infinity.
… that the median of the sample goes to the mean of the theoretical distibution, if the sample size goes to infinity.
… that the relative frequency of an event goes to its probability if the sample size goes to infinity.
… that the absolute frequency of an event goes to its probability if the sample size goes to infinity.

Answer 22

that the relative frequency of an event goes to its probability if the sample size goes to infinity.

Question 23

What is the most important characteristic of the sample statistical parameters (t, F, z, chi square) from the point of view of hypothesis testing?

.. They can be always calculated from the sample, if the right hypothesis test is used.
.. Their probability density function is known.
.. Their distribution is symmetrical, so both one-tailed and two-tailed probabilities can be calculated.
.. Their value is zero if the null hypothesis is true.

Answer 23

They can be always calculated from the sample, if the right hypothesis test is used.

Question 24

We are studying the applicability of a diagnostic test. What is the name of the parameter given by the ratio of true positive tests and all ill people?

• prevalence
• sensitivity
• segregation
• specificity

Answer 24

Sensitivity

Question 25

Standard normal distribution is identical to …

… uniform distribution.
… Student’s t-distribution with infinity degrees of freedom.
… lognormal distribution.
… the Gaussian distribution.

Answer 25

the Gaussian distribution

Question 26

What is the number of degrees of freedom in case of a correlation t-test, if the sample size is 23?

44
23
22
21

Answer 26

21

Question 27

There is a linear function between y and x, if …

… y / x is constant
… x = a · y, where a is a constant (the increment).
… the change in y is proportional to the change in x.
… y = a · x, where a is a constant (the increment).

Answer 27

the change in y is proportional to the change in x

Question 28

Which test may be used if the conditions of the chi-square test are not true?

• Kruskall-Wallis test.
• Correlation t-test.
• ANOVA.
• Fisher’s exact test.

Answer 28

Fisher’s exact test.

Question 29

The probability of occurrence of vascular stenosis among smokers is 0.19. The probability of being a smoker in a given population is 0.29. What is the probability in this population that someone is a smoker with vascular stenosis?

0,655
0,055
Data is too few to answer.
~1

Answer 29

0,055

Question 30

What is your conclusion when the calculated p-value of an F-test is higher than the significance level?

I can accept the nullhypothesis of two-sample t-test.
Variances are equal.
Variances are not equal.
I have to use Mann-Whitney U-test.

Answer 30

Variances are equal.

Question 31

We would like to compare the efficacy of an original drug and a generic one. Choose the correct null hypothesis.

.. The difference between the efficacy of the two drugs is not because of incidence.
.. The efficacy of the generic drug is not significantly different from the original.
.. Incidence has no role in the efficacy difference between the two drugs.
.. The efficacy of the generic drug is not identical to that of the original one.

Answer 31

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

Question 32

Choose the right statement. The y axis intercept of the regression line …

… cannot be less than negative one.
… cannot be more than one.
… cannot be zero.
… can be any real number.

Answer 32

can be any real number.

Question 33

I wanted to use a two sample t-test, but it turned out that the measured variable does not follow normal distriubtion. What test can I use?

Mann–Whitney U-test.
one sample t-test
F-test
Wilcoxon test

Answer 33

Mann–Whitney U-test.

Question 34

Which statement is true? The nullhypothesis is accepted if…

…the calculated p value is less, than the critical one.
…the level of significance is higher, than 5 %.
…the calculated t value is less, than the critical one.
…the level of significance is less, than 5 %.

Answer 34

the calculated p value is less, than the critical one.

Question 35

We want to test with a t-test whether the 35 patients in the hematology ward have the same red cell count as the 35 patients in the contagious ward. What is the number of degrees of freedom?

68
36
34
18

Answer 35

68

Question 36

The absolute value of the correlation coefficient …

… is the square of the covariance.
… is the square root of the determination coefficient.
… is the maximum value of the alpha error of the correlation t-test.
… cannot be zero.

Answer 36

is the square root of the determination coefficient.

Question 37

Pick the correct statement.

.. The condition of t-test for one sample is that the variable to be analyzed follows normal distribution.
.. T-test can only be applied for variables following standard normal distribution.
.. The condition of t-test for one sample is that the variable to be analyzed follows Student’s t distribution.
.. The condition of t-test for one sample is that the standard deviation is one.

Answer 37

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

Question 38

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

t = 0 and p = 1.
p = 0 and t = 1.
t = 100 and p = 1.
t = 0 and p = 0.

Answer 38

t = 0 and p = 1.

Question 39

What is our conclusion if we obtain p = 3.5 in a two-samples t-test?

.. We accept the nullhypothesis considering 5% level of significance.
.. Nothing, we do the calculation again.
.. Since p >1, there is no significant difference between the two groups.
.. We reject the nullhypothesis considering 5% level of significance.

Answer 39

Nothing, we do the calculation again.

Question 40

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

.. They influenced by many independent events, and this, according to the central limit theorem, yields normal distribution.
.. They are all related to each other so they must have the same (or at least similar) distribution.
.. In fact, most of them does not follow normal distribution, and we rather deal with those few which do.
.. They are actually transformed so that they would follow normal distribution which makes them easier to be dealt with.

Answer 40

? Same som en annen?

Question 41

Pick the true statement.

.. The columns of a histogram are called bins, if their areas are proportional to the respective relative frequencies.
.. Histogram is a useful way of data representation, since the area under the curve of a given interval is proportional to the frequency of data in that interval.
.. Only discrete numerical data can be represented with a histogram.
.. The columns of a histogram are called bins, if their heights are proportional to the respective relative frequencies.

Answer 41

The columns of a histogram are called bins, if their heights are proportional to the respective relative frequencies.

Question 42

The expected value …

… is the most probable value of the random variable.
… of a sample is equal to the average of the data.
… of a random variable can be estimated by the arithmetic mean of a sample of its values.
… of the random variable x is the integral of the f(x) function from negative infinity to positive infinity.

Answer 42

is the most probable value of the random variable.

Question 43

What is the relation between the cumulative distribution and probability density functions of a random variable?

.. The cumulative distribution function is the inverse of the probability density function.
.. The cumulative distribution function and the probability density function cannot be given by each other.
.. The probability density function is the derivative of the cumulative distribution function.
.. The probability density function is the integral of the cumulative distribution function.

Answer 43

The probability density function is the derivative of the cumulative distribution function.

Question 44

Quantitative data may be either …

… numerical or discrete.
… counted or discrete.
… measured or continuous.
… continuous or discrete.

Answer 44

continuous or discrete

Question 45

Which one of the following is the characteristic of the (arithmetic) mean?

.. Half of the data of a sample is less than the mean of the sample.
.. The mean is sometimes equal to both the mode and the median.
.. The average of the absolute deviation is minimal if it is measured from the mean.
.. A sample does not necessarily have a mean.

Answer 45

The mean is sometimes equal to both the mode and the median.

Question 46

The consequence of the law of large numbers is …

… that the absolute frequency of an event goes to its probability if the sample size goes to infinity.
… that the median of the sample goes to the mean of the theoretical distibution, if the sample size goes to infinity.
… that the standard error of a sample goes to the standard deviation of thecdorresponding theoretical distribution if the sample size goes to infinity.
… that the relative frequency of an event goes to its probability if the sample size goes to infinity.

Answer 46

that the absolute frequency of an event goes to its probability if the sample size goes to infinity.

Question 47

“A” and “B” are mutually exclusive events. The probability of event “A” is 0,4. What is the probability of event ‘B’?

Maximum 0,6.
Not more than -0,4.
Exactly 0,6.
Minimum 0,4.

Answer 47

Exactly 0,6

Question 48

What is reference interval?

.. An interval determined from a (big) sample: the mean plus/minus the standard deviation.
.. An interval determined from a (big) sample: the mean plus/minus twice the standard deviation.
.. Any interval that contains roughly 68% of the data.
.. Any interval that contains roughly 95% of the data.

Answer 48

An interval determined from a (big) sample: the mean plus/minus twice the standard deviation.

Question 49

There is a linear function between y and x, if …

… y / x is constant
… the change in y is proportional to the change in x.
… x = a · y, where a is a constant (the increment).
… y = a · x, where a is a constant (the increment).

Answer 49

the change in y is proportional to the change in x.