# MCQ-Statistics

Finals Black Bank | Primary Physiology Black Bank | Primary Pharmacology Black Bank

ST01

Mode is a statistical term relating to:

A. Most common number in a group

B. Average value

C. Middle value ie. equal number of values on either side of it

D. ?

ST02 [1985]

For purposes of statistical analysis:

A. The correlation coefficient relates association but not causation

B. The unpaired t-test relates sample means

C. The chi-squared test uses nominal values only

D. Statistical significance does not mean clinical significance

E. All of the above

ST03a [1985] [Aug92] [Mar93] [Aug93] [Mar95] [Apr96] [Jul97] [Apr99] [Aug99] [Mar00]

The Standard Error of the Mean is best described as:

A. The Standard Deviation of sample means

B. An indication of the likelihood of making a type II error

C. Inversely proportional to statistical power

D. Directly proportional to sample size

E. Dependent for its validity on a normal distribution in the population

F. (?) If SD 15 & n 50 then SEM approx 2

ST03b **ANZCA version** [2001-Aug] Q87, [2003-Apr] Q25, [2003-Aug] Q47, [2005-Sep] Q23, [Mar06]

The standard error of the mean is

A. dependent for its validity on a normal distribution in the population

B. an indication of the likelihood of making a type II error

C. about 2, if the standard deviation is 15 and the sample size 50

D. NOT necessary for calculating the confidence interval for the mean

E. the variance of the population of sample means

ST04a **ANZCA version** [2001-Apr] Q38, [2002-Aug] Q26, [2003-Apr] Q38, [Mar06] [Jul06] (*Similar version reported in [Mar93] [Aug93] [Mar94] [Mar95] [Aug95] [Aug96] [Apr97] [Jul97] [Apr98] [Apr99] [Jul00]*)

The power of a statistical test can be expected to decrease, if there is an increase in

A. the sample size

B. the size of the treatment effect

C. the chance of making a Type 1 error

D. the variability of the population

E. none of the above

ST04b **ANZCA version** [2001-Aug] Q117, [2002-Mar] Q122

The power of a statistical test used in a clinical trial is influenced by

1. the sample size

2. sample variability

3. Type Two error

4. level of significance

ST05 [Mar94]

The power of a statistical test is highest when:

A. The expected difference between the 2 groups being compared is large

B. The beta error is less than 5%

C. The study groups are cohort & case controlled

D. Depends on the alpha error & the number of subjects in each study group

ST06 deleted

ST07 [Aug93] [Aug94] [Mar95] [Aug95] [Apr99](type A)

The following data on Apgar scores are best analysed by which test?

Apgar: <4 4-7 >7

Group A 67 55 22

Group B 58 53 8

A. Fisher's exact test

B. Wilcoxon sign rank test

C. ANOVA

D. Chi-squared

ST07b **ANZCA version** [Mar00] [Jul00] [2001-Apr] Q30, [2002-Mar] Q9, [2004-Aug] Q45, [2005-Apr] Q46, [Jul07]

In a clinical trial, 3 out of 10 patients develop a complication in the control group, and 1 of 10 patients develops the complication in the treated group. To assess whether this is a statistically significant difference the most appropriate statistical test to use would be the

A. Chi-square Test

B. Chi-square Test with Yates correction

C. Student's t-test

D. Fisher’s Exact Test

E. Mann-Whitney Test

ST08 [Mar94] [Aug94] [Aug95] [Apr96] [Apr98] [Jul98] [Apr99] (type A)

With regard to statistics:

A. From mean to +/- one sd is 58% of values

B. SEM is standard deviation of the means

C. Variance = the square root of the SD

D. Standard error of the mean = sd / sqrt(n)

E. Median divides the distribution into 2 numerically equal groups

ST09a [Mar94] [Aug94] [Apr98] (type K)

Double blind clinical trial: (?conduct of.. ?reason for..)

A. Cohort studies & case control studies both subject to bias

B. Involves randomisation

C. Blinding of an independent observer

D. Involves blinding of the investigator

E. Complies with the Helsinki agreement on ethics

F. Patient not aware of treatment

ST09b **ANZCA version** [2001-Apr] Q110

Therapeutic clinical trials are often double-blind to

1. ensure that the patient is unaware of the form of treatment that he is receiving

2. conform with the Helsinki Code for clinical trials

3. ensure that the observer is unaware of the form of treatment being administered

4. ensure that there is genuinely random allocation of patients to treatment and control groups

ST10a **ANZCA version** [Aug95] [Apr96] [Aug96] [Jul00] [2001-Apr] Q31, [2003-Apr] Q128, [2003-Aug] Q24

When a new diagnostic test is evaluated in a group of subjects in whom the diagnosis is known, the following results are obtained Disease known to be present Disease known to be absent New test result positive 2 4 New test result negative 6 8 The specificity of the new test is closest to A. 25% B. 33% C. 57% D. 67% E. 75%

ST10b **ANZCA version** [2002-Mar] Q13

When a new diagnostic test is evaluated in a group of subjects in whom the diagnosis is known, the following results are obtained Disease known to be present Disease known to be absent New test result positive 50 20 New test result negative x 80 If a subject from this population tests positive, the probability of having the disease is approximately A. 0.8 B. 0.7 C. 0.6 D. 0.5 E. cannot be calculated because 'x' is unknown

ST11 [Aug94] [Aug96] [Apr97] [Jul97] [Apr99]

Which of the following best describes the number of cases of a disease in a given population at a specific time:

A. Incidence

B. Occurrence

C. Frequency

D. Prevalence

E. Rate

ST12 [Mar93] [Jul97]

During interpretation of a report of a clinical trial the:

A. Most important factor in determining the statistical power of the study is the size of the expected difference between the groups being compared

B. Statistical power of the study is the probability of not making a type II error

C. 99% confidence interval for the population mean is given by the sample mean +/- 1.96 x standard error of the mean

D. Designs least subject to bias are cohort and case control studies

E. Validity of the results is questionable if serial comparisons were made between the two samples using ANOVA (analysis of variance).

ST13 [Apr96] [Apr97] [Apr98] [Jul98] (type A)

Comparing two anti-hypertensive agents (or test on a new antihypertensive agent)

Study reports 95% confidence interval for the difference between the two drugs is 2 to 10 mmHg. The conclusion is:

A. There is no statistically significant difference because the confidence interval is small

B. There is a statistically significant difference (p< 0.05) because the confidence interval does not include zero.

C. There is a statistically significant difference (p< 0.01) because the confidence interval does not include zero

D. There is a clinically significant difference

ST14a [Apr96] [Apr98] [Jul98] [Apr99]

Based on the information in the 2x2 contingency table, what is the chance of having the disease if the test is positive? Disease Yes No Test Positive 80% 10% Negative 20% 90% A. 0.89 B. 0.8 C. 0.67 D. 0.5 E. <0.3 D. ?

ST14b [Jul99] [Mar00]

What is the chance of having the disease if the test is positive? Disease Yes No Test Positive 0.5 0.2 Negative X 0.8 A. 0.89 B. 0.71 C. ? D. ? E. Cannot determine without knowing ‘X’

ST14c **ANZCA version** [2001-Aug] Q72

When a new diagnostic test is evaluated in a group of subjects in whom the diagnosis is known, the following results are obtained. Disease known Disease known to be present to be absent Test result positive x y Test result negative 30 60 If a subject from this population tests negative, the probability of NOT having the disease is A. unable to be calculated because “x” is unknown B. unable to be calculated because “y” is unknown C. unable to be calculated because “x” and “y” are unknown D. 0.33 E. 0.67

ST15 [Aug96] [Apr99]

Concerning the odds ratio with regard to treatment:

A. Odds ratio of 1.0 means no association

B. Odds ratio of 2.0 means half the effect

C. Odds ratio 0.5 if increase risk 50%

D. Odds ratio of 0.0 means no association

Also remembered as:

In regard to odds ratio:

A. If odds ratio 1.0, no significant contribution

B. If odds ratio 3.0, there is 3 times less chance of disease

C. If odds ratio 0.5, 50% increased chance of disease

D. If odds ratio 0.0, no significant contribution

ST16 **ANZCA version** [2005-Sep] Q42 (*Similar version reported in [Apr98] [Apr99] [Mar00] [Jul00]*)

A placebo should be used in a clinical trial when

A. observer bias is possible

B. a type one error is probable

C. an acceptable standard treatment is not known to exist

D. a placebo effect is anticipated

E. human patients are used as subjects

ST17 [Mar00]

In normal distribution:

A. Mode and mean are the same

B. 98% lie within 2 standard deviation

C. Supplying mean and standard deviation describes the distribution

D. Transformed has sd of 1

ST18 **ANZCA version** [2001-Apr] Q70, [2001-Aug] Q43, [2003-Apr] Q86, [2003-Aug] Q60, [2005-Sep] Q41

Which of the following alternatives is correct regarding the range of values that odds ratios (OR) and relative risks (RR) can take?

A. OR (0 to positive infinity); RR (0 to positive infinity)

B. OR (negative infinity to positive infinity); RR (negative infinity to positive infinity)

C. OR (0 to 1); RR (0 to 1)

D. OR (0 to positive infinity); RR (negative infinity to positive infinity)

E. OR (0 to positive infinity); RR (negative 1 to positive 1)

ST19 **ANZCA version** [2002-Mar] Q62, [2002-Aug] Q59, [2005-Apr] Q58, [2005-Sep] Q50

A diagnostic test has a sensitivity of 90% and a specificity of 99% in detecting a certain disease. From this we can conclude that

A. the false positive rate of this test is 1%

B. the false negative rate of this test is 1%

C. the positive predictive value of this test is 90%

D. the negative predictive value of this test is 90%

E. this test would be a useful screening test for this disease

ST20 **ANZCA version** [2001-Aug] Q83, [2002-Aug] Q78, [Apr07] [Jul07]

In a trial, 75 patients with an uncommon, newly described complication and 50 matched patients without this complication are selected for comparison of their exposure to a new drug. The results show Complication present Complication absent Exposed to new drug 50 25 NOT exposed 25 25 From this data A. the relative risk of this complication with drug exposure CANNOT be determined B. the odds ratio of this complication with drug exposure CANNOT be determined C. the relative risk of this complication with drug exposure is 2 D. the odds ratio of this complication with drug exposure is 1.33 (recurring) E. none of the above

ST21 **ANZCA version** [2002-Aug] Q122, [2003-Aug] Q87, [2004-Apr] Q67, [Apr07] Q87, [Jul07]

Forty patients are randomly dived into two groups - one to receive induction agent A and another to receive induction agent B. The next day they are asked to rate their anaesthetic experience on a scale of 1 (very bad) to 5 (very good). The most appropriate test to compare the anaesthetic experience of the two groups is the

A. unpaired t-test

B. Mann-Whitney test

C. Chi-square test

D. Kruskal-Wallis test

E. paired t-test

ST22 **ANZCA version** [2002-Aug] Q81, [2004-Apr] Q88, [2004-Aug] Q78

Recognised weaknesses of systematic reviews include all of the following EXCEPT

A. publication bias

B. duplicate publication

C. study heterogeneity

D. inclusion of outdated studies

E. systematic review author bias

ST23 deleted - same as ST02

ST24 **ANZCA version** [2003-Aug] Q108, [2004-Apr] Q62, [Mar06]

In a group of subjects, the proportion vomiting is 80%. With treatment, this can be reduced to 60%. The number needed to treat (NNT) with this treatment is

A. 3

B. 4

C. 5

D. 6

E. 7

ST26 **ANZCA version** [2004-Apr] Q91, [2004-Aug] Q74, [Jul06] [Apr07]

Correct statements regarding confidence intervals (CI) include all the following EXCEPT

A. CI are derived from the standard error (of the mean).

B. CI can be used to assess the precision of population parameter estimates.

C. The width of the CI depends on the degree of confidence required.

D. The width of the CI depends on the sample size.

E. The width of the CI depends on the mean value of the sample

ST27 [x]:

Side effect No side effect

Drug given 5 2 Drug not given 1 5 Odds ratio is A. 1 B. 4 C. 8 D. 12.5 E. cannot calculate

ST28 **ANZCA version** [2004-Apr] Q115, [2004-Aug] Q50, [Jul06]

One hundred vomiting patients receive ondansetron. If 25 patients, who would not have stopped vomiting had they received a placebo, stop vomiting, then the number needed to treat (NNT) for ondansetron to stop vomiting is

A. 1.3

B. 4

C. 25

D. 100

E. can't be calculated without information on placebo success rate

ST29 deleted - same as ST22

ST30 **ANZCA version** [2002-Mar] Q130

If two methods of measuring a physiological parameter have a Pearson correlation co-efficient of 0.99 one could conclude that

1. there is a strong linear association between the two methods of measurement

2. there is good agreement between the two methods of measurement

3. increases in the value of one measurement will usually be associated with increases in the value of the other measurement

4. the two measurements probably use a similar methodology

ST31 **ANZCA version** [2005-Apr] Q130

Which of the following statements about "bias" in scientific studies is FALSE?

A. bias is a systematic deviation from the truth

B. observer bias can be eliminated by blinding

C. randomisation is one of the most important ways to reduce bias

D. the Hawthorne effect may be reduced by masking the actual intent of a study

E. triple-blinding refers to the blinding of patient, observer and investigator

ST32 [Jul06] [Apr07]

If a new test is developed for a particular disease, the best way to determine its SPECIFICITY is to:

A. find a sample of people, some of whom have the disease and some who do not

B. find a sample of people, all of whom do not have the disease

C. find a sample of people, all of whom do not have the disease, and compare to the estimate of population prevalence

D. find a sample of people, all of whom have the disease

E. find a sample of people, all of whom have the disease, and compare to the estimate of population prevalence

ST33 **ANZCA version** [2004-Aug] Q129

Six patients with an uncommon but newly described complication are selected, and 7 matching patients without this complication are selected, to determine their exposure to a new drug. The results are shown in this table. Complication Present absent Exposed to new drug 5 2 Not exposed to new drug 1 5 The odds ratio of having the complication with exposure, compared with non-exposure, to the new drug is A. unable to be accurately calculated B. 0.08 C. 0.5 D. 2 E. 12.5

ST34 [Mar06]

Disease No Disease Test +ive 80 40 Test -ive 20 180 What is the positive predictive value of the following test A. 33% B. 50% C. 66% D. 80%

ST35 [Apr07]

Test positive Test Negative Disease present 80 20 Disease absent 20 180 Negative predictive value is: A. 10% B. 80% C. 90% D. E.

ST36 [Jul07]
Publication bias is:

- A. Publication of papers by more known authors
- B. Publication of papers with negative results
- C. Publication of papers with positive results
- D. Publication of papers because the study was published by a prestige journal
- E. The publisher decides what to print

ST37 [Aug10] Negative predictive value is best described as

- A.
- B. Chance of a negative test in people without a disease.
- C.
- D.
- E.

ST38 [Mar10]
Specificity most closely means:

- A. Chance of a positive test in people with the disease
- B. Chance of a negative test in people without the disease
- C. (?)... (
*Chance of me ever understanding statistics =0%*) - D. ??Men with hats
- E. ??Chance of Bon Jovi.