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RESS Flashcards

1
Q

What is incidence?

A

Measures number of new cases that occur over a specified time period in a population at risk. Number of new cases ÷ number of new people at risk during the specified time period. If time period is one year: ‘annual incidence’.

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1
Q

Why sample nigga

A
  • Cost - Utility – might not want the entire pop (some may be more informative), may have sufficienct power sampling a subset, may want to reuse samples elsewhere and the two are incompatible. - Accessibility – might not be able to sample entire pop, some people unable/unwilling to partake, some people’s data will be incomplete.
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1
Q

How to calculate odds ration?

A

Odds ratio for two groups = odds of event for exposed individuals ÷ odds of event for unexposed individuals.

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2
Q

For populations/samples n

A

Use the students’ t distribution (slightly fatter bell curve) - we must estimate the population SD

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3
Q

What is cause specific mortality?

A

Cause-specific mortality (proportion of deaths attributable to a specific cause) = number of cases with this disease who die ÷ total number of any cause deaths

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3
Q

Pros and cons of prospective data collection?

A

 Helps ensure that you record all the variables you need, using best techniques available, applied consistently.  Helps enseure all participants provide data on all variables (reducing missingness).  CON - Time-intensive  CON - Resource intesnvie  CON - Tendency to collect data on more variables than you actually need or can use in your analyses.

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4
Q

What is the usual accepted cut off for something to be significantly different from the null hypothesis?

A

p

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4
Q

Why calculate power? (before conducting study and after concluding that no effect found)

A

 Be sure study is well designed  To (thereby) justify study to grant reviewers etc.  Demonstrate you were sufficienctly well-powered to detect an effect  To estimate that, if there is an effect, how small it must be for it to be missed.

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4
Q

What are the key principles of ethical research?

A

 The project is conducted in compliance with an explicit protocol.  An authorised research ethics committee has approved the protocol.  Further research ethics committee approval is requested if: - There are any substantial changes to the project protocol - The project has any unexpected deleterious effects

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5
Q

What is risk?

A

Risk = ‘probability’: the proportion of a population or sample with the outcome or exposure

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6
Q

Ways of summarising and describing variables?

A

Frequency tables, bar charts/pie charts, average values, distribution of values, histograms

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8
Q

what is an audit?

A

quality improvement process that seeks to improve patient care and outcomes through a systematic review of care against explicit criteria (evidence-based clinical standards).

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9
Q

What are histograms?

A

Very similar to bar charts but can only be drawn for continuous variables or ordinal categorical variables. Offer visual representation of distribution of frequency as value of continuous (or ordinal categorical) variable increases.

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9
Q

What is the study sample?

A

the units/participants drawn from the target population that constitute our data set.

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10
Q

What is a variable?

A

a characteristic or ‘parameter’ for which a ‘sample statistic’ can be calculated as an estimate of the population parameter.

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11
Q

What is overall mortality?

A

Overall mortality (proportion of pop who die) = number of deaths (regardless of cause) ÷ number of people in population

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11
Q

Possible sources of measurement error

A

 Inherent variation/instability in the variable  The use of a proxy for a latent variable  Poor quality measurement equipment/technique  Self-reported/interviewer-generated information  Response bias – what interviewer wants/gets  Prestige bias – what appears favourable  Recall bias – what is accurately remembered  (Multiple) transcription from source(s) to proforma

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12
Q

Three questions to identify study design?

A

Q1. What was the aim of the study? - Combine findings from more than one study – Meta-analytical - Describe a population - Descriptive - Quantify relationships between variables – Analytical (go to Q2) Q2. Was the intervention/exposure allocated by researcher? - Yes - Trial - No - Observational study (go to Q3) Q3. When was/were the outcome(s) determined? - Some time after the exposure/intervention? – Cohort - At same time as exposure/intervention? – Cross-sectional - Before the exposure/intervention determined? - Case-Control

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13
Q

What does qualitative research aim to do?

A

Access the experiences of others

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14
Q

As prevalence declines what happens to OR and RR?

A

RR changes, OR stays the same

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15
Q

What is fatality?

A

Fatality = number of cases who die ÷ number of cases with the disease

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15
Q

What should a project protocol provide sufficienct evidence to do?

A

 Enable project team members to conduct the project  Prospective project participants to assess whether to volunteer  Research ethics committee members to approve, refer or reject.

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16
Q

What are high risk ethical issues?

A

 Vulnerable study participants  Covert data collection  Sensitive topics  Administering drugs/food/fluid  Conducting potentially harmful/painful procedures  Collecting biological body materials  Abnormal psychological stress  Prolonged or repetitive testing  Material or financial participation incentives  Data transfer outwith the European Union  Conflicts of interest  Potential risks to researchers, non-participants or the environment  Animal (Scientific Procedures); Human Tissues; Data Protection Acts

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18
Q

What are 3 basic person characteristics that can determine disease risk?

A

Sexxxxxxxxx, class, age

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19
Q

What’s a fucking sample?

A

A collection of data drawn from a population

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20
Q

What is odds? What is odds risk?

A

Odds similar to risk when proportion of the population/sample with the outcome or exposure is low. BUT odds risk is stable as outcome prevalence changes.

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20
Q

What is a type I error?

A

You find an effect when there is no genuine effect - oh what fun!

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20
Q

What is power?

A

Probability of finding an effect if there is one to be found

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20
Q

When are confidence intervals smaller?

A

We have less variation in our data We have a larger sample size

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21
Q

Potential sources of measurement bias?

A

 Information bias – extent of information varies amongst participants. Priori hypothesis and primary data collection.  Observer bias – influenced by prior knowledge or belief. Blinded, independent, objective or validated.  Recall/response/prestige bias – influenced by prior knowledge or belief. Blinded.

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23
Q

Problem with pie charts?

A

can be visually complex when there are large numbers of classes or when the frequency of some classes is very low.

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25
Q

What is person time?

A

Number of people at risk can vary during the time period. Epidemiological concept that multiples number of people at risk at various points across time period and uses this as the denominator in any calculation of incidence.

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26
Q

How do you assess which covariates are important?

A

what are the (likely) causes of the exposure? What are the (likely) causes of the ‘outcome’? Which are (likely to be) caused by the ‘exposure’? Think conceptually and operationally about which covariates we would like/be able to measure.

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27
Q

What is a sample?

A

a subset of a population, intended to be representative of that population, from which we can explore the population by ‘inference’

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28
Q

What does a mediator do?

A

 Causes the outcome  Is caused by the exposure  Must not be adjusted for because it is on the causal pathway

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29
Q

Is qualitative research time consuming?

A

Yes

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30
Q

Types of projects that do require formal ethical approval?

A

 Non-human subjects/material covered by the Animals (Scientific Procedures) Act 1986  Service Evaluations involving vulnerable participants or ethically sensitive topics  Projects involving a new intervention – Experimental Research  Projects collecting new information on more than only service delivery – Non-Experimental Research

31
Q

What should a project protocol aim to explicitly describe

A

 WHY the project is necessary/justified (i.e. it is an important issue, that has not been examined before or needs verification)  WHAT the project will involve (i.e. how data will be collected, how, when and from and by whom; and how these data will be analysed).  HOW key ethical, legal and governance issues will be avoided, addressed or mitigated in the design and conduct of the project.

32
Q

3 types of clinically relevant studies

A

Audit, service evaluation, research

32
Q

What is population?

A

every member of a defined group of interest

33
Q

5 types of potential stakeholders?

A
  1. Other researchers/evaluators/auditors 2. Research/evaluation/audit funders 3. Clinical practitioners/policy-makers 4. Service users 5. Society at large
33
Q

Types of qualitative study?

A

 Existing sources – examined post hoc. Text (website, leaflet, newspapers), audio (radio, film scores…), video (youtube, documentary, cct).  New sources – examined de novo. Individuals (one to one interviews), groups (focus groups, ethnographic observation).

35
Q

For chronic diseases will prevalence or incidence be higher?

A

Prevalence will be higher than incidence for diseases of long duration – chronic diseases.

36
Q

What is a latent variable?

A

Missing variable.

37
Q

When is there greater power?

A

Same factors that affect size of confidence intervals - mean effect is bigger, variation in effect is smaller, sample is bigger

38
Q

What is the epidemiological triad

A

Person, time, place

38
Q

In what studies is risk used?

A

Cohort (incidence)

39
Q

What does priori registration do?

A
  • Helps reduce publication bias and selective reporting - Helps reduce unnecessary duplication and fosters better collaboration (including prospective meta-analysis) - Helps identify gaps in planned/ongoing research - Helps facilitate recruitment of participants - Helps screen for errors/weakness in research design.
41
Q

For what kind of variables can you estimate confidence intervals?

A

Normally distributed

43
Q

Three types of samples?

A
  • Complete samples – entire study population - Unstratified random sampling – every member of the target population has same chance of being samples. - Stratified random sampling – randomly sample from the target population within strata (groups). Every member of the target population within each stratum has the same chance of being sampled. Usually numbers in each stratum in proportion to size of strata but may over sample (e.g. comparing two groups).
44
Q

What is prevalence?

A

Measures number of cases that exist at a specified time point in a population at risk

45
Q

As prevalence increases what happens to OR and RR?

A

OR >> RR

46
Q

For incurable diseases will prevalence or incidence be higher?

A

Will increase at same rate

47
Q

What does a confounder do?

A

 Causes the outcome (dependent variable)  Causes the exposure (independent variable)

48
Q

What does missingness do?

A

reduces number of participants on whom you have complete data, and therefore the ‘realised’ sample size that can be achieved in any analyses containing these variables

50
Q

For populations/samples n>200 what do we use for confidence intervals?

A

use the ‘normal’ distribution and its z statistic value of 1.96. (we know the population SD)

51
Q

What is a stakeholder?

A

Stakeholder = people who have an interest in the results of research. Important to communicate research to them as effectively as possible.

53
Q

Frequency distribution histograms take what sort of curve?

A

Normal/bell curve

54
Q

Three descriptions of a ‘causal’ relationship?

A

 Functional (no contraception –> teenage mother)  Theoretical (teenage grandmother –> teenage mother)  Speculative (teenage grandfather –> teenage mother)

55
Q

What does a competing exposure?

A

 Causes the outcome  Is unrelated to the exposure

56
Q

What is checking?

A

Whether sampling is stratified or not there are usually features that you hope will be ‘representative’ of the target population. These can be used to check sample is representative.

57
Q

What’s the target population?

A

total finite population we wish to know about and from which the sample is drawn.

58
Q

Pros and cons of retrospective data collection?

A

 Data collection is less time-intensive and less resource-intensive  CON – not role in choosing which variables are measured, in choosing the number of participants, in the consistency/inconsistency of measurement, in the level of ‘missingness’ tolerated.

59
Q

Odds ratio = 1?

A

No effect bitch

60
Q

In what studies is odds used?

A

Case-control/trial (prevalence)

61
Q

What is a bar chart?

A

simple visual summary of frequency/relative frequency of cases/events that can also include confidence intervals.

62
Q

What do you need to know to calculate power?

A

 The effect size in your population.  The variability of the effect in your population  What sample size will/can you collect  Then calculate the probability that the observed effect in your sample will be significant (i.e. Confidence interval does not cross zero).

64
Q

What is relative frequency?

A

counts expressed as a percentage of the total number of counts

66
Q

For diseases of short duration will incidence or prevalence be higher?

A

Incidence will be higher than prevalence for disease of short duration – infectious diseases.

67
Q

What are the four main types of variable?

A

Categorical - nominal, ordinal Numerical - discrete, continuous

68
Q

Possible source of dissemination bias?

A

 Publication bias – eventful results more likely to be published. Priori registration and meta-analysis.

69
Q

Mnemonic for defining search terms used in literature searches?

A

PECOS - Patient/Participant/People - Exposure/Event/Experimental intervention - Comparison (if appropriate) - Outcome - Study design (appropriate for question)

70
Q

What is ethics/governance/consent?

A
  • Ethics = ensuring that projects minimise risks and maximise benefits - Governance – ensuring that projects have appropriate permission(s) - Consent = ensuring participation is voluntary and without cost
72
Q

Type II error?

A

Fail to find an effect when there is a genuine effect - boo hoo!

74
Q

What is a service evaluation?

A

evaluates a proposed service or current practice with the intention of generated information to inform local decision-making.

75
Q

What is the p value?

A

the probability of seeing the result we have observed or something more extreme if the null hypothesis is true – this probability is the p-value

76
Q

Potential sources of sampling/selection bias? And solutions?

A

 External validity: non-representative samples. Use stratified/random sampling, and/or multi-site  Confounding – selection influences exposure and outcome. Use matching, adjustment or random sampling.

77
Q

Potential sources of analytical bias?

A

 Loss to follow-up: specific participants excluded. Intention to treat.  Omitted variable bias – imprecise adjustment for confounding. Priori hypothesis and primary data collection.  Attributional bias – interpretation of causality. Priori design.

78
Q

Aims of research ethics committees?

A

 Aim to ensure that the projects they approve…  Minmise the risk of harm to project staff, participants and society  Complies with relevant legal and regulatory requirements  Complies with requirements of professional indemnity insurance

79
Q

The less residual variation (noise) on a line graph…

A

the better the fit of the model and the more confident we will be (so the more statistically significant the correlation between the two variables will be).

80
Q

What don’t you want in a questionnaire proforma?

A

 Ambigious questions – “Would you normally feel uncomfortable about your diabetes?”  Leading questions – “In what ways is diabetes a problem for your family?”  Multiple questions – “Have you found diabetes to be a limiting, longstanding illness?”

82
Q

Possible sources of missingness?

A

 Non-routinely collected viarbles  (Clinically) unimportant/irrelevant variables  Variables that are difficult/costly to collect  Variables that require invasive or potentially sensitive measurement (that undermines acceptability/measurement complicance)

83
Q

What is frequency?

A

number of cases/events expressed as if they were ‘counts’

84
Q

What does a DAG identify?

A
  • Identify any measured/able ‘covariates’ acting as ‘confounders’ – so these can be adjusted for. - Identify any measured/able ‘covariates acting as ‘competing exposures’ – so these can be adjusted for - Identify any measured/able covariates acting as ‘mediators’ – so these are not adjusted for.
85
Q

What is research?

A

Derives generalizable new knowledge by addressing clearly defined questions with systematic and rigorous methods.

86
Q

Types of projects that do not require formal ethical approval?

A

 Data/material already published/publicly available – Secondary Research  Projects on non-human subjects/materials – Non-Human Research  Projects using only existing service management data – Audit  Projects collecting new information only on service delivery – Service Evaluation

87
Q

Methods of dissemination?

A

 Researchers/evaluators/auditors – journals (more prestigious = broader readership), conferences.  Funding bodies – regular reports.  Clinicians/policy makers – journals, conferences, professional associations.  Service users – via clinicians, focus groups/participants, press, online, leaflets.

88
Q

What are parameters that can influence disease risk?

A

Time of day, week, month, year, life (age

89
Q

What are adjustments?

A

Corrections made to sample statistics to make them… - Better estimates of true population values (e.g. when sample is not truly representative of population of interest). - Comparable to other samples/populations with different baseline characteristics (different age/sex structures).

90
Q

What does adjustment involve?

A

Adjustment involves calculating ‘stratum-specific’ rates by key characteristics (at least by age and sex) and weighting these rates in proportion to the distribution of these characteristics in the real or a standard population.

91
Q

How do we engage with stakeholders during study planning, implementation and dissemination?

A

 Study planning – patient steering groups, (peer) advisory committees, pilot studies.  Implementation – continued feedback, monitoring  Dissemination

92
Q

What is a dag?

A

A pikey dog. Nah not really… type of ‘causal path diagram’ with unidirectional (‘causal’) arrows linking variables and no circular paths. - Summarise the functional, theoretical and speculative relationships between variables pertinent to our question.

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