Final 2

Question 1

􏰳 the outcome of the 6th toss is heads?
It is (1/2)^6 = 1/64.

It is(1/2)÷6=1/12.

It is 50%.

Not enough data to tell.

Answer 1

its is 50%

Question 2

􏰴 Which of the following is a measure of spread?
Median.

Mean.

Mode.

Range.

Answer 2

Range

Question 3

A t-test for paired values is executed during the evaluation of an experiment. The sample has 24 elements. Choose the correct degrees of freedom.

23

46

11

24

Answer 3

46

Question 4

Choose the correct statement(s).

In medical practice, confidence level usually corresponds to 95% probability.

The confidence level can be chosen freely.

The confidence interval contains 95% of the data.

The confidence interval contains 68% of the data.

Answer 4

The confidence level can be chosen freely.

Question 5

Choose the correct statement(s).

The size of a sample is proper if the calculated F-value is approx. 1.

In the case of proper sampling, the type I error is less than 5%.

The size of the sample is proper if its relative frequency distribution is not significantly different from the probability distribution of the population.

In the case of proper sampling both the type I and type II errors are less than 5%.

Answer 5

The size of the sample is proper if its relative frequency distribution is not significantly different from the probability distribution of the population.

Question 6

The p-value calculated in a Wilcoxon test is 0.145. Choose the correct statement(s).

The difference between the medians is significant in 85.50% of all cases.

The difference between the medians is insignificant in 85.50% of all cases.

The null hypothesis can be accepted, i.e. there is no significant difference between the values measured before and after the treatment.

The null hypothesis should be rejected, i.e. the difference between the values measured before and after the treatment is significant.

Answer 6

The null hypothesis can be accepted, i.e. there is no significant difference between the values measured before and after the treatment.

Question 7

What is the aim of a test for independence?

• It tests whether the means are independent form the choice of group.
• Tests the effect of risk factors.
• Tests whether the probabilities of possible outcomes of a quality are independent of the presence of an other effect.
• Tests whether two random variables are independent.

Answer 7

Tests whether the probabilities of possible outcomes of a quality are independent of the presence of an other effect.

Question 8

What is the probability of a certain event?

0.

1.

Infinity.

0.5.

Answer 8

1

Question 9

The applicability of a diagnostic test is being studied. What is the name of the parameter that is given by the ratio of true negative and all negative results?

Specificity.

Negative predictive value.

Positive predictive value.

Sensitivity.

Answer 9

Negative predictive value.

Question 10

What is the degree of freedom in a chi-square test for homogenity, if the aim is to tell whether the distribution of male and female in 4 hospitals is uniform?

1

2

3

6

Answer 10

3

Question 11

The aim of a t-test is to tell whether the red cell count of 23 patients in the hematological ward and of 23 patients in the contagious ward is the same? What is the degree of freedom?

12

44

22

24

Answer 11

44

Question 12

In which case(s) is it appropriate to use Wilcoxon sign test?

• To test the change of a non-parametric variable in two paired samples.
• To compare the parametric variable of two samples with different numbers of elements.
• To test normally distributed numerical variables in one sample.
• To compare the non-parametric variable of two samples with different numbers of elements.

Answer 12

• To test the change of a non-parametric variable in two paired samples.

Question 13

The result of a fit test for normal distribution is P = 0.485. Choose the correct decision.

• Since p > 0.05, the null hypothesis is accepted, therefore the sample is not normally distributed.
• The null hypothesis is rejected, therefore the sample follows a non-normal distribution.
• p > 0.05, consequently the null hypothesis is rejected and the distribution of the sample does not deviate from normal distribution.
• The null hypothesis is accepted, the tested sample fits to normal distribution.

Answer 13

The null hypothesis is accepted, the tested sample fits to normal distribution.

Question 14

Choose the false statement(s).

• Significance level gives the probability that the rejected null hypothesis is true.
• Significance level gives the probability that the accepted null hypothesis is false.
• Significance level is equivalent with the type I error.
• Significance level gives the percentege of data outside the normal range.

Answer 14

Significance level gives the probability that the rejected null hypothesis is true.

Question 15

What is the correct decision if the sample p-value is 0.022, and the critical p-value is 0.095?

The alternative hypothesis is false.

The null hypothesis is rejected.

The null hypothesis is accepted.

The null hypothesis is true.

Answer 15

The null hypothesis is rejected.

Question 16

Choose the true statement(s).

If the number of elements of a sample is increased, the standard deviation goes to zero.

Confidence level is given with the mean and the sample standard deviation.

Standard error is a parameter used in the estimation of expected value.

If the number of elements of a sample is increased, the standard error goes to the theoretical standard deviation.

Answer 16

Standard error is a parameter used in the estimation of expected value.

Question 17

Null hypothesis is rejected if ..

… the sample statistical parameter is less than the critical statistical parameter.

… the significance level (considering a two tailed test) is more than 5%.

… the significance level is less than 5%.

… the sample statistical parameter is greater than the critical statistical parameter.

Answer 17

… the sample statistical parameter is greater than the critical statistical parameter.

Question 18

The probability of event “A” is 0.57. What is the maximum possible probability of event ‘B’ if events ‘A’ and ‘B’ cannot happen at once?

Exactly -0.57.

Precisely 43%.

It can be anywhere between 0 and 1.

It can be anywhere between 0 and 0.43.

Answer 18

It can be anywhere between 0 and 0.43.

Question 19

􏰵 Choose the definition of frequency in statistics.

• The frequency of an event is equal to the count of its occurrence in the population.
• The frequency of an event is equal to the count of its occurrence per unit time.
• The frequency of an event is equal to the count of its occurrence in a series of observations.
• The frequency of an event is equal to the count of observations.

Answer 19

The frequency of an event is equal to the count of its occurrence in a series of observations.

Question 20

􏰶 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?

Discrete numerical.

Categorial.

Exponential.

Not enough information to decide.

Answer 20

Categorial.

Question 21

􏰷 “A” and “B” are mutually exclusive events. The probability of event “A” is 0,31. What is the probability of event ‘B’?

Minimum 0,31.

Not more than -0,31.

Maximum 0,69.

Exactly 0,69.

Answer 21

Maximum 0,69.

Question 22

􏰸 Choose the right statement on type II error.
The null hypothesis is accepted, although it is false. 1 Gives the error of wrong decision. 0 The alternative hypothesis is accepted, although it is false.

Question 23

􏰹 We would like to compare the efficacy of an original drug and a generic one. Choose the correct null hypothesis.
The efficacy of the generic drug is not significantly different from the original.

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

Question 24

􏰺 Pick the correct statement.
The condition of t-test for one sample is that the variable to be analyzed follows normal distribution.
The condition of t-test for one sample is that the standard deviation is one. 0 T-test can only be applied for variables following standard normal distribution. 0

The condition of t-test for one sample is that the variable to be analyzed follows Student’s t
distribution.

Question 25

􏰓 In which case should one reject the null hypothesis?
If the absolute value of the statistical parameter calculated form the sample is greater than the
absolute value of the critical statistical parameter. 1

If the p-value calculated from the sample is greater than the critical p-value. 0

1

If the p-value calculated from the sample is greater than 5%. 0 If the absolute value of the statistical parameter calculated from the sample is greater than 5%. 0