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Epidemiology SJSM > Block 4 final > Flashcards

Block 4 final Flashcards

1
Q

Three groups of subjects were followed over the course of five years to compare the efficacy of different pharmacologic effects of treatments for sideroblastic anemia. The most appropriate statistical analysis to determine the qualitative differences resulting from these treatments would be a…

a) Regression analysis
b) Chi-square
c) F-test (ANOVA)
d) T-test
e) Correlation analysis

A

c) F-test (ANOVA)

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2
Q

A 56 yr old man with chronic pancreatis has a serum alanine aminotransferase (ALT) level of 100 U/L. How is the lab value best described as a variable?

a) Categorical, ordinal
b) Quantitative, discrete
c) Quantitative, continuous
d) Categorical, nominal

A

c) Quantitative, continuous

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3
Q

Which of the following statements describes a type II error?

a) Rejecting the null when H0 is false
b) Accepting the null when H0 is false
c) Rejecting the null when H0 is true
d) Accepting the null when H0 is true

A

b) Accepting the null when H0 is false

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4
Q

A correlation between two variables measures the degree to which they are…
a) Positively skewed
b) Mutually exclusive
c) Causally related
d) Statistically significant
e) Associated

A

e) Associated

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5
Q

Which of the following analytical models is best suited to predict the expected weight of infants suited to predict the expected weight of infants in their first year according to their age in months?

a) Simple regression
b) Logistic regression
c) Multiple regression
d) Cox proportional hazards regression
e) Correlation

A

a) Simple regression

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6
Q

A physician is studying the effects of Drug A & Drug B on disease X. A test is administered to a group of two subjects (those taking Drug A & those taking Drug B) and compares their mean scores. Which of the following statistical tests is appropriate for this purpose?

a) T-test
b) Z-score
c) ANOVA
d) Chi-Square test

A

a) T-test

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7
Q

A correlation coefficient of zero indicates…

a) Statistical significance
b) That there is a possible weak association
c) Causation
d) As the X-axis variable changes so does the Y-axis variable
e) That the two variables are not related

A

e) That the two variables are not related

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8
Q

A researcher is testing a new, experimental drug designed to reduce blood pressure. What is the alternate hypothesis of the research trial?

a) The experimental drug is not clinically useful
b) The experimental drug increases blood pressure
c) The experimental drug does not have an effect on blood pressure
d) The experimental drug decreases blood pressure
e) The experimental drug has major side effects

A

d) The experimental drug decreases blood pressure

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9
Q

A researcher found that as vegetable consumption went up, cancer rates went down. How are these two variables related?

a) Zero correlation
b) Vegetable consumption protects against cancer
c) Negative correlation
d) Position correlation
e) No relationship

A

c) Negative correlation

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10
Q

A researcher wants to evaluate the effect of changing titrations dosage of blood pressure medication on blood pressure. In this experiment, what kind of variable is “dosage of blood pressure medication”?

a) Random
b) Fixed
c) Dependent
d) Independent
e) Categorical

A

d) Independent

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11
Q

A study conducted to examine the relationship between daily caffeine intake and systolic blood pressure. The calculated correlation coefficient r measures which of the following?

a) The statistical significance of the association between daily caffeine intake and blood pressure
b) The likelihood that caffeine intake and systolic blood pressure are mutually exclusive
c) The degree of association between the two study variables
d) The extent to which caffeine intake and blood pressure are causally related

A

c) The degree of association between the two study variables

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12
Q

Which of the following values of the Pearsons correlation coefficient (r) best represents an association between two variables which is describes as moderate negative correlation?

a) +0.6
b) -0.6
c) -0.3
d) +0.4
e) +0.9

A

b) -0.6

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13
Q

Which of the following best represents the correlation coefficient between systolic blood pressure and age as negligible?

a) +0.70
b) +1.20
c) -0.22
d) -.85
e) 0

A

e) 0

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14
Q

Studying the association between plasma levels of renin and changes in blood pressure, a researcher would obtain the most effective use of the data by the application of:

a) Correlation analysis
b) Students t-test
c) F-test
d) Chi-square test
e) Analysis of the variance

A

a) Correlation analysis

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15
Q

Comparing the blood hematocrit value before and after delivery, which of the following statistical tests will be most appropriate to be used?

a) ANOVA
b) Chi square
c) paired t-test
d) Pearson correlation
e) T-test

A

c) paired t-test

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16
Q

Describe a null hypothesis

A

No statistically significant relationship between two variables

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17
Q

Describe a null value of 1 is used for which two values

A

Relative risk (cohort)
Odds ratio (case-control & cohort)

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18
Q

Describe a null value of 2 is used for which two values

A

Attributable risk
Absolute risk reduction

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19
Q

Relative risk describes the

A

probability of an outcome occurring in an exposed group

more than 1 = positive association (increased risk)

Less than 1 = decreased risk (protective)

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20
Q

Odds ratio

A

AD/BC

it measures the association between an event/outcome (case-control)

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21
Q

describe Attributable risk

A

(incidence in exposed) - (incidence in unexposed)

The absolute risk that can be attributed to an exposure/risk factor

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22
Q

Describe Absolute attributable risk

A

(risk in non-exposed) - (risk in exposed)

The difference in risk attributed to an exposure/outcome compared to a non-exposure

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23
Q

P value less than/equal to 0.05

A

Statically significant (accept alternative)

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24
Q

P value more than 0.05

A

Reject alternative

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25
Q

Describe a type I error

A

We reject the null when it’s actually true

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26
Q

Describe a type II error

A

We fail to reject the null (accept) when it’s false

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27
Q

Describe statistical power

A

(1-B), it’s the probability of correctly rejecting the null (aka accuracy)

28
Q

How do you increase statistical power?

A

Increase sample size

29
Q

Related vs unrelated groups

A

related= share a risk factor

unrelated = don’t share a risk factor

30
Q

Pearson correlation coefficient:

weak correlation

A

r= 0.2-0.5 (+/-)

31
Q

Pearson correlation coefficient:

moderate correlation

A

r= 0.6-0.8 (+/-)

32
Q

Pearson correlation coefficient:

strong correlation

A

r= 0.8-1 (+/-)

33
Q

The closeness of test results to the true values.
The absence of systematic error or bias in a test

A

Accuracy (validity

34
Q

Accuracy (validity) describes

A

The closeness of test results to the true values.
The absence of systematic error or bias in a test

35
Q

What decreases the accuracy of a statistical test

A

Systematic error

36
Q

The consistency and reproducibility of a test.
The absence of random variation in a test.

A

Precision (reliability)

37
Q

What decreases the precision of a test

A
  • Random error
38
Q

Precision (reliability) describes

A

The consistency and reproducibility of a test.
The absence of random variation in a test.

39
Q
A

Strong negative correlation (0.8-1)

40
Q
A

Weak negative correlation (0.2-0.5)

41
Q
A

No correlation

42
Q
A

Weak positive correlation (0.2-0.5)

43
Q
A

Strong positive correlation (0.8-1)

44
Q

Describe simple regression

A

Relationship between 2 variables

45
Q

Describe multiple regression

A

The relationship between 2 or more variables

46
Q

Qualitative, Ordinal

A

Categorical values with categories that have logical order

47
Q

Qualitative, Nominal

A

Categorical values with categories that have NO order

48
Q

Quantitative, Discrete

A

Numerical values that can be counted

49
Q

Quantitative, Continuous

A

numerical values that can’t be counted (lab values)

50
Q

Describe a t-test

A

Checks the difference between the means of 2 groups

Numerical variables

51
Q

Describe a paired t-test

A

Checks the difference between the means of 2 groups which are related

Numerical variables

52
Q

Describe an un-paired t-test

A

Checks the difference between the means of 2 groups which are NOT related

Numerical variables

53
Q

Describe an ANOVA/F-test

A

Checks the differences between means of 3 or more groups

54
Q

Describe a Z-test

A

Used for 1 group with categorical data. It compares populations with different means and standard deviations

55
Q

Describe Z-score

A

Shows how many standard deviations from the mean the actual value is

56
Q

Z score of 95% is

A

1.96

57
Q

Z score of 99.7% is

A

2.58

58
Q

How many Standard deviations from the mean is 99.7% Z-score is indicative of

A

3 std

59
Q

How many Standard deviations from the mean is 95% Z-score is indicative of

A

2

60
Q

How many Standard deviations from the mean is 68% Z-score is indicative of

A

1

61
Q

Describe the Chi-square test

A

For 2 or more groups with 2 or more categorical categories,

It checks the differences between 2 or more proportions of categorical outcomes

62
Q

“Compare the proportion of members of 3 age groups who have hypertension” would need which statistical test

A

CHI-SQUARE test

63
Q

Describe McNemars test

A

2 groups of paired categorical data (only has 2 categories)

64
Q

How can you increase the power of a statistical test?

A

1) Increase sample size
2) Increase the expected effect
3) Increase precision of measurement

65
Q
A

Bimodal = 2 subgroups in the population

66
Q
A

Positive skew (Right)
Mean>med>mode

67
Q
A

Negative skew (left) mean<med<mode

Epidemiology SJSM (5 decks)

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