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x F2: EBM > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

Descriptive stats purpose

A

Summarize or describe the main features of a dataset
(Central tendency, measures of spread, data visualization)

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2
Q

Inferential stats purpose

A

Makes inferences and predictions about a population based on a sample
(Hypothesis testing, confidence intervals, p values)

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3
Q

Random sampling

A

All members of the population have an equal chance of being selected

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4
Q

Cluster sampling

A

Selecting random samples from certain natural groupings

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5
Q

Systematic sampling

A

Selecting every random individual from a list

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6
Q

Convenience sampling

A

Selecting a population based on convenience of the investigator

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7
Q

Hypothesis testing

A

Used to make inferences or decisions about a population based on sample data
Allows to test assumptions and determine if there is enough evidence to support a claim

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8
Q

Null hypothesis testing (H0)

A

States there is no stat difference between groups
Goal to disprove or reject the null hypothesis
Test this first then test alternative

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9
Q

Alternative hypothesis testing (H1)

A

Suggests there is a stat difference between groups
Hope to prove or accept alternative hypothesis

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10
Q

What is a type 1 error

A

False positive
Occur when null hypothesis is incorrectly rejected
Denoted by alpha**
(When alpha = 0.05 then 5% chance of making a type 1 error)

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11
Q

What is a type 2 error

A

False negative
Occurs when null hypothesis is incorrectly accepted
Means that no difference when there is one
Donated by beta
(Risk of type 2 error increases with a smaller sample size)

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12
Q

If p < alpha the null is what

A

Rejected (significant result)

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13
Q

If p > alpha the null is what

A

Null is not rejected (not significant)

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14
Q

What is power calculation

A

The probability of correctly rejecting the null hypothesis
Power = 1 - Beta
Higher power reduces type 2 error, increase sample size boosts study power

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15
Q

If beta is 0.2 then the study power is what? If beta is 0.1 the power is what

A

80%
90%

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16
Q

Stat significance is or is not equal to clinical significance

A

Is NOT

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17
Q

Confidence intervals (CI)

A

Range of numbers likely to contain the population interval
A method to determine stat significance: studies may report CI, p-value, or both
(Usually reported as 95% confidence interval)

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18
Q

If evaluating differences between groups the CI cannot cross what? If evaluating proportions, RR or OR, the CI cannot cross what?

A

0
1

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19
Q

Is normally distributed parametric or non-parametric

A

Parametric
(Non normally distributed is non parametric)

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20
Q

What is students t-test

A

Parametric test
Have to be normally distributed and continuous data
Random samples from two independent populations
Compares means***

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21
Q

What is a paired t-test

A

Determine differences between the same individuals (dependent or paired)
Dependent variable is normally distributed and continuous
Compares means

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22
Q

What is analysis of variance (ANOVA)

A

3 or more independent samples
Continuous parametric data

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23
Q

What is Mann Whitney U (Wilcoxon Rank Sum test)

A

Two independent samples
Ordinal and continuous non parametric data

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24
Q

Wilcoxon signed ranks

A

Two related paired samples
Ordinal and continuous non parametric data

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25
Q

Kruskal Wallis

A

3 or more independent samples
Ordinal and continuous non parametric data

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26
Q

Chi squared test

A

Two independent samples or 3 or more independent samples
Nominal data

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27
Q

Fishers exact test

A

Two independent samples
nominal data

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28
Q

McNemar

A

Two related paired samples
Nominal data

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29
Q

Subgroup analysis

A

Explores treatment across different subgroups of a population
Goal to see if effect of treatment is consistent across all groups

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30
Q

Univariate analyses

A

Comparison of one dependent variable to one independent variable
-doesn’t account for confounders
-may have stat significant results that are not accurate

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31
Q

Multi variable analysis

A

Compare one dependent variable to multiple independent variables
-multiple variable = confounders or covariants
-able to determine stat significance

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32
Q

Multi variable linear regression

A

Dependent variable is a continuous variable
Independent variables can be nominal, ordinal, or continuous
P values will be provided for each covariant and the relationship to the dependent variable

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33
Q

What is multicollinearity

A

Correlations exist between the variables indicating redundancy and potential bias (relationship exists between variables)

34
Q

Multi variable logistic regression

A

Dependent variable is dichotomous variable
Independent variable can be nominal, ordinal, or continuous
Relationship is non linear

35
Q

Survival analysis

A

Methods to determine time to an event
If event is not experienced subject is surviving
If event is experienced subject is failing
Dependent variable is time

36
Q

Censoring meaning

A

Done for incomplete data
-If subjects are lost to follow up or do not have event they are censored
-data for that patient included up until end of study or lost to follow up

37
Q

Kaplan Meier method

A

Survival analysis
-can’t account for relationship of covariates on survival
-analysis cannot determine if the independent variable predicts survival

38
Q

Kaplan Meier method

A

Estimation of survival curve

39
Q

What are the two ways to present the Kaplan Meier method

A

Survival function: cumulative frequency of subjects not experiencing event
Hazard function: cumulative frequency of subjects experiencing the event

40
Q

Cox proportional hazards model

A

Stat comparison accounting for covariates

41
Q

Log rank test

A

Stat comparison

42
Q

Matching test (Propensity score matching)

A

cases matches to controls based on investigator determined factors
help remove differences in baseline characteristics and only evaluate study question

43
Q

IRB definition

A

Committee ensuring all study subjects are protected and not exposed to unnecessary harm and/or unethical medical procedures

44
Q

True or False: all research projects that use humans as study subjects must be IRB approved before beginning study enrollment

A

True
Aka ethics committee

45
Q

At time of study enrollment, a study subject needs to be given an informed consent form that informs them of what 6 things

A

Study procedures
Rights and responsibilities for study participation
Risk/benefit of study population
Compensation for study participation
Participation in the study is voluntary
Right to withdraw from the study

46
Q

Cohort studies: subject grouping is done via what

A

Exposure
(Different from case control studies)

47
Q

What is the importance of a cohort studies follow up

A

Subjects followed to determine the incidence of an outcome (symptom, disease, death)

48
Q

Relative risk

A

The risk of developing a disease or event in subjects exposed to a variable versus those not exposed to

49
Q

Prospective cohort study (aka concurrent)

A

Subjects identified based on current OR past exposure and then followed for a period of time to determine if subject had the predetermined outcome

50
Q

Retrospective study (aka non concurrent)

A

Exposure and outcome have already occurred
Data obtained from a database to determine patient exposure and outcomes

51
Q

Ambidrectional cohort study

A

RARE cohort study design
Subjects identified and outcomes assessed in the past and future

52
Q

Confounders

A

Variable (factor) that influences or is related to other variables in the study

53
Q

How to fix no randomization in cohort studies

A

Limit inclusion/exclusion criteria

54
Q

Prospective studies in cohort studies are subject to ______ from more intensive monitoring

A

Bias

55
Q

Case control studies: subject grouping is done by what

A

Outcome
(Subjects with outcome are compared to similar subjects without the outcome)

56
Q

Case control studies follow up importance

A

Data collected from subjects with and without outcome to determine if they experiences the exposure
(Via patient interview or survey OR by reviewing data records)
Both exposure and outcome known at start of study

57
Q

Odds ratio

A

Estimate of the relative risk
(Done in case control studies evaluation)

58
Q

Retrospective case control study

A

Exposure and outcome has already occurred
Data obtained from a database or pt interview to determine patient exposure and outcomes

59
Q

How to use case control studies in practice

A

Identify risk factors of a disease, benefits and safety risks of both med and procedure
For rare disease
Less expensive

60
Q

Is randomization possible in case control studies

A

No

61
Q

How to fix case control studies randomization issues

A

Matching
(Cases matches to controlled based on investigator determined factors)

62
Q

Outcome measurements may not be accurate in case control studies what can you do with study investigators to confound for this

A

Blind them to subjects exposure status when determining outcome

63
Q

One technique to overcome historical data not being as accurate is to assign multiple controls to one case patient to help minimize bias, what study is this in

A

Case control

64
Q

In cross sectional studies data is only collected at ____ time point for all subjects

A

ONE

65
Q

How is evaluation determined in cross sectional studies

A

Descriptive stats (mean or median)

66
Q

How to use cross sectional studies in practice

A

Useful for measuring current health status or disease control

67
Q

What study design is good for hypothesis generating

A

Cross sectional

68
Q

Inclusion criteria similarities between RCT and observational studies

A

Subject demographics or characteristics that MUST be present in order to be enrolled in study

69
Q

Impact on study findings similarities between RCT and observational studies

A

Inclusion and exclusion criteria impact study validity

70
Q

What is active control

A

Standard of care

71
Q

Composite endpoints

A

Group of endpoints that are considered clinically important
Primary or secondary endpoints
Measure overall effect of therapy
Overstate results of study

72
Q

Surrogate endpoint

A

An endpoint that is associated with an outcome but does not directly measure it

73
Q

Subgroup analysis

A

Dividing the study population into subsets of participants based on common characteristics

74
Q

What study is single case, 3 or fewer cases, more than 3 cases

A

single case: case report
3 or fewer cases: case series
more than 3 cases: cohort study

75
Q

What studies are not under the jurisdiction of IRB

A

Case studies and case series

76
Q

Importance of case reports

A

Generation of new hypothesis
Improvement of medical education
Early benefits or harm that might take additional time if reviewed in a more formal setting
Medical writing and editing skills

77
Q

What study describes an account of an individual clinical case that is accosted with an uncommon presentation, clinical course, or outcome

A

Case report

78
Q

What study should allow the reader to critique and reach conclusions about the case prior to reading the discussion section of the manuscript

A

Case report

79
Q

What are the contents of a case report

A

Title
Background
Patient case
Discussion
Conclusion

80
Q

For case studies do you have to write a report for each patient

A

Yes need to write a report for every person you do, you cannot add them all in one report

x F2: EBM (2 decks)

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