Quiz
PUBH Important Concepts
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Questions in this quiz (35)
1You can protect randomisation in an RCT by 1) concealing allocation and 2) using intention to treat analysis
- ATrue
- BFalse
2If you do not follow intention to treat analysis, what do you follow?
- APer protocol analysis
- BRandom analysis
- CDefective route analysis
3Potential sources of bias:
[blank_start]Lack of blinding[blank_end] - if participants/researchers know which treatment
[blank_start]Loss to follow up[blank_end] - no data/someone leaves study, could underestimate harms of treatment
[blank_start]Non-adherence[blank_end] - if people do not follow protocol, may not learn of efficacy- ALack of blinding
- BLoss to follow up
- CNon-adherence
4_______ is the genuine uncertainty about a benefit or harm of intervention.
- AClinical equipose
- BClinical equity
5[blank_start]Internal validity[blank_end] comprises of if the findings are real or if they could be explained by chance, bias, or confounding. [blank_start]External validity[blank_end] is considered afterwards and evaluates the generalisability of a study.
- AInternal validity
- BExternal validity
6As sample size increases, likelihood of getting a representative sample [blank_start]increases[blank_end]. The accuracy of the parameter estimates also [blank_start]increases[blank_end] i.e. 95% confidence interval has a [blank_start]smaller[blank_end] range.
- Aincreases
- Bdecreases
- Cincreases
- Ddecreases
- Esmaller
- Flarger
7Which statement best explains confidence intervals?
- AA CI represents the range of values the true parameter will lie in 95% of the time (if we continue to repeat with the same samples)
- BA CI represents the range of values the true parameter will exist in (if we continue to repeat with the same samples)
- CA CI is used to estimate a true average
8When interpreting 95% CI, if the null value [blank_start]lies within[blank_end] the interval, then the findings are consistent with chance as an explanation and are [blank_start]not statistically significant[blank_end].
If the null value [blank_start]does not lie within[blank_end] the interval, then it is unlikely the value is due to chance and so it is [blank_start]statistically significant[blank_end].- Alies within
- Bdoes not lie within
- Cnot statistically significant
- Dstatistically significant
9The null hypothesis (Ho) states there is [blank_start]no association[blank_end] between exposure and outcome. The alternate hypothesis (Ha) states there is [blank_start]an association[blank_end].
P values test the null hypothesis. P values are the probability that differences are due to chance if the [blank_start]null hypothesis[blank_end] is true.- Ano association
- Ban association
- Cnull hypothesis
10The p value is the probability that null hypothesis or alternate hypothesis is true.
- ATrue
- BFalse
11A Type I error is finding a statistically significant result when there is actually [blank_start]no association (Ho is true)[blank_end]. There occur [blank_start]5%[blank_end] of the time if we use 0.05 as a p value.
A Type II error is finding a statistically significant result where there actually is [blank_start]an association (Ha is true)[blank_end].- Ano association (Ho is true)
- Ban association (Ha is true)
- Can association (Ha is true)
- Dno association (Ho is true)
- E5%
- F105
12Which concept is described by "any systematic error which results in an incorrect estimate between the exposure and risk of disease"?
- ABias
- BConfounding
- CChance
13Of the three main types of bias, which can only be controlled for in the design phase?
- ASelection and information bias
- BInformation and publication bias
- CSelection and recall bias
14Selection bias is a [blank_start]systematic[blank_end] difference between 1) people included in the study vs. not or 1) people included in the [blank_start]exposure vs. control[blank_end] groups.
Loss to follow up can create a selection bias. To minimise loss to follow up, you can collect [blank_start]alternate[blank_end] details when recruiting participants, maintain [blank_start]regular[blank_end] contact with participants, and make [blank_start]several[blank_end] contact attempts.- Asystematic
- Bexposure vs. control
- Calternate
- Dregular
- Eseveral
15Case-control studies are susceptible to [blank_start]recall bias and selection bias[blank_end]. Since the exposure and outcome have already occurred, and cases and controls are selected [blank_start]separately[blank_end], it is important that selection is [blank_start]independent[blank_end] of exposure status.
When selecting cases, you must ensure high [blank_start]participation[blank_end], have a clearly defined [blank_start]population of interest[blank_end], and have a reliable method of ascertaining cases.
When selecting controls, you must ensure the controls are from the [blank_start]same[blank_end] defined population, and have the same inclusion/exclusion [blank_start]criteria[blank_end] as the cases, and once again ensure high participation.- Arecall bias and selection bias
- Bseparately
- Cindependent
- Dpopulation of interest
- Eparticipation
- Fsame
- Gcriteria
16Measurement error creates [blank_start]information[blank_end] bias. A participant, interview technique, or data collection instrument could cause measurement error.
Measurement error can be systematic or random. Accurate data is collected when there is no [blank_start]systematic[blank_end] error. Precise data is collected when there is no [blank_start]random[blank_end] error.- Ainformation
- Brecall
- Csystematic
- Drandom
17An accurate but unprecise study had little to no systematic error, but had random errors.
- ATrue
- BFalse
18Non-differential misclassification is systematic i.e. misclassification occurs [blank_start]equally between groups[blank_end]. Differential misclassification means that groups had [blank_start]different levels of misclassification[blank_end].
- Aequally between groups
- Bdifferent levels of misclassification
19Which of these is not a method to minimise recall bias?
- AUsing objective measures
- BValidating self reported measures with other information
- CUsing memory aids
- DStructured questionnaire and standard prompts
20Which of these is not a method of minimising interviewer bias?
- AClearly defined study protocol
- BInterviewer training
- CBlinding
- DObjective measures
21Confounders are: associated with the exposure, associated with the outcome, but not on the causal pathway.
- ATrue
- BFalse
22The Simpson's paradox is when a confounder reverses the association between an exposure and outcome.
- ATrue
- BFalse
23Ways to reduce confounding at the design phase:
1. [blank_start]Restricting[blank_end] who can enter the study
2. [blank_start]Randomisation[blank_end] of groups (eg RCT)
3. [blank_start]Matching[blank_end] (1:1 or frequency)- ARestricting
- BRandomisation
- CMatching
24Ways to control for confounding at the analysis stage:
1. [blank_start]Stratification[blank_end] (grouping)
2. [blank_start]Standardisation[blank_end]
3. Regression models/[blank_start]Multivariable analysis[blank_end]- AStratification
- BStandardisation
- CMultivariable analysis
25It's possible to over-match when matching.
- ATrue
- BFalse
26Steps of a systematic review:
1. [blank_start]Formulation of a clear question[blank_end]
2. Develop [blank_start]search[blank_end] strategy
3. [blank_start]Diagnostic test[blank_end] strategy
4. Search for and [blank_start]identify relevant studies[blank_end]
5. [blank_start]Data extraction[blank_end]
6. [blank_start]Individual and group crit. appraisal[blank_end]
7. [blank_start]Synthesis of findings[blank_end]
8. [blank_start]Interpretation of results[blank_end]- AFormulation of a clear question
- Bsearch
- CDiagnostic test
- Didentify relevant studies
- EData extraction
- FIndividual and group crit. appraisal
- GSynthesis of findings
- HInterpretation of results
27Choose the incorrect statement about levels of prevention.
- APrimordial prevention is establishing and maintaining conditions that minimise harm to health.
- BPrimary prevention aims to limit the incidence of disease by controlling risk factors.
- CSecondary prevention aims to reduce the prevalence of disease, by shortening duration, severity, and occurrence.
- DTertiary prevention aims to reduce the time spent with disability.
28Examples of types of prevention:
[blank_start]Secondary[blank_end] = Weight loss programmes
[blank_start]Primary[blank_end] = reduce HIV cases by promoting condoms
[blank_start]Primordial[blank_end] = reduce car crash injuries by providing good infrastructure for cycling
[blank_start]Tertiary[blank_end] = Stroke rehabilitation- ASecondary
- BPrimary
- CPrimordial
- DTertiary
29An exposure with a large population attributable risk is a good target for intervention.
- ATrue
- BFalse
30Choose the incorrect statement about prevention.
- AIndividual prevention has a favourable benefit-to-risk ratio.
- BIndividual prevention is behaviourally inappropriate.
- CPopulation prevention is radical.
- DPopulation prevention is radical is behaviourally appropriate.
- EPopulation prevention is has a high benefit-to-risk ratio.
31Surveillance can be [blank_start]universal[blank_end] (the whole population) or [blank_start]sentinel[blank_end] (in certain sites eg labs). It can also be [blank_start]active[blank_end] (an established system) or [blank_start]passive[blank_end] (based on health care worker reports).
- Auniversal
- Bsentinel
- Cactive
- Dpassive
32When deciding if screening is appropriate we must consider:
1) [blank_start]The seriousness of the disease[blank_end] (ie don't screen for colds)
2) The ability to [blank_start]alter the course of disease[blank_end]
3) [blank_start]Lead time[blank_end] (in what period can we detect the disease)
4) [blank_start]Prevalence of preclinical disease[blank_end]- AThe seriousness of the disease
- BPrevalence of preclinical disease
- CLead time
- Dalter the course of disease
33A screen test has good [blank_start]sensitivity[blank_end] if it has a high ratio of people diagnosed with the disease, over all people with the disease - diagnosed and undiagnosed. (a / a+c or, true positives / false negatives + true positives)
A screen test has good [blank_start]specificity[blank_end] if it has a high ratio of people without the disease diagnosed as disease free, over all people with the disease. (d / b+d or, true negatives / false positives + true negatives)- Asensitivity
- Bspecificity
34Sensitivity & specificity are [blank_start]intrinsic[blank_end] properties of the test. Predictive values measure test [blank_start]performance[blank_end] in a
particular population. The positive predictive value is the true positives over the true positives and false negatives ([blank_start]a / a+b[blank_end]). The negative predictive value is the true negatives over the false positives and true negatives ([blank_start]d / c+d[blank_end]).- Aintrinsic
- Bperformance
- Ca / a+b
- Dd / c+d
35Predictive values are influenced by disease prevalence.
- ATrue
- BFalse
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- Description
- Quiz on PUBH Important Concepts, created by Mer Scott on 25/10/2017.
- Author
- Mer Scott
- Language
- English
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