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Jaspie - Prev Med II > Biostatistics and Methods of Epidemiology > Flashcards

Biostatistics and Methods of Epidemiology Flashcards

1
Q

What is the appropriate measure of central tendency in qualitative data such as gender, religion, or nationality?

A

Mode

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2
Q

4, 6, 2, 2, 4, 3, 2, 1, 7
Mean?
Median?
Mode?

A

Mean
Median 3
Mode 2

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3
Q

Average

Sum of observations divided by the number of observations

A

Mean

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4
Q

The observation that occurs with greatest frequency

A

Mode

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5
Q

Middle observation in a series of ordered observations

e.g. the 50th percentile

A

Median

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6
Q

Epidemiology can be defined as the study of the ___ and determination of ___ of disease in ___

A

distribution
frequency
humans

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7
Q

What is the sampling unit in epidemiologic studies in the identification of causal factors?

A

A group of individuals

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8
Q

The ultimate goal of an EPIDEMIOLOGIC INVESTIGATION: To institue ___, ___, and ___ to avoid more cases

A

curative
preventive
control measures

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9
Q

Studies both the DISTRIBUTION OF DISEASES in human populations and the DETERMINANTS OF THE OBSERVED DISTRIBUTION

A

Epidemiology

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10
Q

Epi?

Demos?

A

Upon

People

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11
Q

Began as the study of infectious diseases

A

Epidemiology

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12
Q

Epidemiology began as the study of infectious diseases. Later on, it expanded to include the study of ___ disease, ___ of health care, ___ of health care, and ___ and ___ health

A 
chronic
organization
delivery
occupational
environmental
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13
Q

Study of the distribution of diseases in animals

A

Epizootiology

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14
Q

Antigenic drift or shift?

Most likely the cause of changes in a certain strain that allows infection despite adequate vaccination

A

Antigenic drift

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15
Q

Antigenic drift or shift?

Partial immunity or mutation to a less virulent strain

A

Antigenic drift

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16
Q

A sudden change in the molecular structure of a microorganism and produces new strains. This results to little or no acquired immunity to these new strains and is the explanation for new epidemics or pandemics (novel strains)

A

Antigenic drift

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17
Q

A slow and progressive change in the antigenic composition of microorganisms. this alters the immunological responses of individuals and a populations susceptibility to that microorganism

A

Antigenic drift

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18
Q

This would decrease the rate of infection by decreasing the probability that a susceptible person would come into contact with an infected person.
Would this affect the clinical presentation of those infected? Y/N

A

Herd Immunity

No

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19
Q

Community’s Reaction to Disease:

Occurrence of a number of cases of disease in excess of normal occurrence of expectancy

A

Epidemic

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20
Q

Community’s Reaction to Disease:

Epidemic involving many countries

A

Pandemic

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21
Q

Community’s Reaction to Disease:

Occurrence of few and unrelated cases

A

Sporadic

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22
Q

Community’s Reaction to Disease:

Constant occurence

A

Endemic

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23
Q

No cases on record, disease not there from the beginning, disease has been eradicated e.g. small pox (Variolavirus 1980)

A

Absence of disease

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24
Q

Association between LBW and maternal smoking during pregnancy
What type of study to be used?

A

Cohort

25
Q

Study:
Exposure and outcome are measured at the same point in time
E.g. prevalence study

A

Cross sectional

26
Q

Study:

Prospective studies in which an intervention is applied

A

Clinical trials

27
Q

Refers to the groups of subjects who are followed forward in time to see which ones develop the outcome

A

Cohort

28
Q

Study:
Clinical characteristic or outcome form a single clinical subject or event (n=1)
Control: none

A

Case Report

29
Q

Study:
Prevalence study
Determines in each member of the population the presence or absence of a disease and other variables at one point in time
Control: none

A

Cross Sectional

30
Q

Study:
Assesses the association of risk factor and disease
Causality cannot usually be determined

A

Cross Sectional

31
Q

Study:
Clinical characteristic or outcome from a group of clinical subjects or evens (n>1)
Control: none

A

Case Series

32
Q

Study:

Population group exposed to a risk factor is followed over time compared with a group not exposed to the risk factors

A

Cohort

33
Q

Study:
Outcome is disease incidence in each group
Prospective
To establish causality

A

Cohort

34
Q

Study:
Can determine icidence and causal relationships if there is statistical association between risk factor and disease
Control: Population at risk versus population not at risk

A

Cohort

35
Q

Study:
Very useful for studying conditions which very low incidence or prevalence
Rare diseases

A

Case-control

36
Q

Study:

Weak establishment of causality

A

Case-control

37
Q

Study:
Identifies a group of people with the disease (case) and compares them with a suitable comparison group without the disease (control)

A

Case-control

38
Q

Study:
Retrospective
Assesses many risk factors for disease
Can help determine causal relationships — but weakly

A

Case-control

39
Q

Study:
Weakest because outcome has already happened
Cannot assess incidence and prevalence of disease

A

Case-control

40
Q

E.g. Study of the causes of a rare form of leukemia; limited funding; large database that is only a few years old
What study will you recommend?

A

Case control

41
Q

Problem of Cohort study?

What question does a cohort study answer?

A

Loss to follow up and attrition

What will happen?

42
Q

Problem of Case control study?

What question does a case control study answer?

A

Recall

What is happened?

43
Q

What question does a cross sectional study answer?

A

What is happening?

44
Q 
A new screening test is applied to a representative sample of 1000 people in the population.
Positive diseased: 90
Positive well: 60
Negative diseased: 10
Negative well: 840
Sensitivity?
Specificity?
PPV?
A

Sensitivity: how many true positives among diseased?
90/100
90%
SNOUT

Specificity: how many true negatives among well?
840/900
SPIN

Positive predictive value: how many diseased among positives?
90/150

45
Q 
A new screening test is applied to a representative sample of 1000 people in the population.
Positive diseased: 90
Positive well: 60
Negative diseased: 10
Negative well: 840
Sensitivity?
Specificity?
PPV?
A

Sensitivity: how many true positives among diseased?
90/100
90%
SNOUT

Specificity: how many true negatives among well?
840/900
SPIN

Positive predictive value: how many diseased among positives?
90/150

46
Q

Total number of cases in a population at a given time; all cases, old or new; chronic

A

Prevalence

47
Q

Number of new cases in a population per unit time; new, acute

A

Incidence

Incidence is new incidents

48
Q

Number of true positives divided by number of all people with disease

A

Sensitivity

PID: positive in disease (PID is a sensitive topic!)
SNOUT: sensitivity rules out

49
Q

High sensitivity is desirable for a ___ test, to rule ___!

A

SCREENING

OUT

50
Q

High specificity is desirable for a ___ test, to rule ___!

A

CONFIRMATORY

IN

51
Q

Number of true negatives divided by the number of all people without the disease

A

Specificity

NIH: negative in heath
SPIN: sensitivity rules in

52
Q

Number of true positives divided by the number of people who tested positive for the disease

A

PPV

53
Q

The probability of having a condition given a positive test. “Is it really positive?”

A

PPV

54
Q

An increase in PPV will lead to an/a ___ in prevalence

A

increase

55
Q

Number of true negatives divided by the number of people who tested negative for the disease

A

NPV

56
Q

The probability of not having a condition, given a negative test. “Is it really negative?”

A

NPV

57
Q

Unlike sensitivity and specificity, predictive values are dependent on the ___ of a disease. The higher the ___ of a disease, the ___ the PPV

A

prevalence
prevalence
higher

58
Q 
E.g. The absence of valvular calcification in an adult suggests that severe valvular aortic stenosis is not present. --- Valvular calcification is/has:
Sensitive?
Specific?
High PPV?
Low NPV?
A

Sensitive

Sensitive test: one that is positive in most patients with disease. If the absence of a characteristic rules out a disease, then the test is sensitive; hardly anyone with the disease has a negative test

Jaspie - Prev Med II (5 decks)

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