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Yr 3 - RESS3 > RESS Curriculum > Flashcards

RESS Curriculum Flashcards

1
Q

Define statistical significance

A

The likelihood that the results obtained in a study were not due to chance alone (p values and confidence intervals may be used to assess statistical significance).

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2
Q

Define a p value

A

The probability that the observed difference between two treatment groups might have occurred by chance.

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3
Q

What does a p value <0.05 indicate?

A

If the p value <0.05 then the observed difference between the groups is so unlikely to have occurred by chance that we reject the null hypothesis (that there is no difference) and accept the alternative hypothesis that there is a real difference between the treatment groups.

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4
Q

Define a heuristic

A

Any approach to problem solving that employs a practical method that is not guaranteed to be optimal, perfect, or rational, but is nevertheless sufficient for reaching an immediate, short-term goal or approximation

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5
Q

What is the hierarchy of evidence?

A

A heuristic used to rank the relative strength of results obtained from scientific research.

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6
Q

Down side of hierarchy of evidence?

A

this focuses exclusively on ‘effectiveness’ and rarely pays attention to the quality of the studies

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7
Q

What is the pyramid shape used to illustrate in the hierarchy of evidence?

A

Increasing risk of bias

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8
Q

What is a case control study?

A

Selects participants on the basis of their outcome and works back to their exposure

E.g. patients who have developed a disease are identified and their past aetiological factors is compared with that of controls who do not have the disease.

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9
Q

In a case control study, the controls are used to estimate the exposure distribution (i.e. the proportion having the exposure) in the population from which the cases arose.

How is the odds ratio then calculated?

A

The exposure distribution in cases is then compared to the exposure distribution in the controls in order to compute the odds ratio as a measure of association

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10
Q

Advantage of case control studies?

A

Cheap

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11
Q

Main disadvantage of case control studies?

A

Prone to selection bias

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12
Q

Why are case control studies prone to selection bias?

A

Selection bias occurs when subjects for the ‘control’ group are not truly representative of the population that produced the cases.

May occur when ‘cases or controls are included/excluded from a study because of some characteristic they exhibit which is related to exposure to the risk factor under evaluation.

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13
Q

When is selection bias in case control studies a particular problem?

A

Where cases and controls are recruited exclusively from hospital/clinics → hospital patients tend to have different characteristics than the population e.g. higher levels of alcohol/smoking

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14
Q

What is a cohort study

A

Longitudinal study; an exposure is assessed (common characteristic) and then participants are followed prospectively to observe whether they develop the outcome

  • Selects participants before outcome
  • No control over outcome
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15
Q

What type of study is one that looks at the potential long-term consequences of the use of oral contraceptives?

A

Cohort study

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16
Q

What is a prospective study

A

Studies are planned in advance and carried out over a future period of time

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17
Q

What is a retrospective study

A

study looks at data that already exists and try to identify risk factors for particular conditions

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18
Q

Which type of study is used to try and identify risk factors for particular conditions?

A

Retrospective studies

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19
Q

What is a randomised controlled trial?

A

A number of similar people are randomly assigned to 2 (or more) groups to treatment groups (e.g. drug).

  • One group has the intervention being tested (the experimental group)
  • The other has an alternative intervention (placebo) or no intervention at all (the control group)
  • The groups are followed up to see how effective the experimental intervention was
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20
Q

What can RCTs control?

A

Used to control factors not under direct experimental control

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21
Q

Which study type is regarded as the gold standard trial for evaluating the effectiveness of interventions?

A

Randomised controlled trials → is the most scientifically rigorous method of hypothesis testing available

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22
Q

Disadvantage of RCTs?

A

Expensive

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23
Q

Why is the RCT considered to provide the most reliable evidence on the effectiveness of intervention?

A

Because the processes used during an RCT minimise the risk of confounding factors influencing the results

The findings are likely to be closer to the true effect than the findings generated by other research methods.

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24
Q

What is meta analysis?

A

A method often used in systematic reviews to combine results from several studies of the same test, treatment or other intervention to estimate the overall effect of the treatment (a formal study of existing evidence).

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25
Define research
Generates **new knowledge** where there is no (or limited) research evidence available and which has to potential to be generalizable or transferable
26
Define an audit
A **quality** **improvement** process that seeks to improve patient care and outcomes
27
What is the aim of an audit?
Quality improvement (patient care and outcomes)
28
How does an audit seek to improve quality of care?
Systematic review of care against **_explicit criteria_** and the implementations of change → **Existing** **practice** is measured against **evidence**-**based** **clinical** **standards** (explicit criteria).
29
What is a service evaluation?
Evaluates a **current service** or **proposed practice** to assess **how well a service is achieving its intended aims**.
30
What is the sole purpose of a ervice evaluation?
sole purpose of **defining or judging** the current service
31
Audit vs service evaluation?
A **clinical audit** is designed to answer the question → ‘*Does this service reach a certain standard?’* A **service evaluation** is designed to answer the question → ‘*What standard does/might this service achieve?’*
32
What is an audit-cum-service evaluation?
Many studies conduct both an **audit** (to establish the extent to which clinical practice is achieving a particular _standard_) as well as a **service** **evaluation** (to establish what _factors_ might be associated with those contexts)
33
Example → NICE guidelines recommend swallowing therapy “*at least three times a week for as long as they continue to make functional gains*”
_Study 1 AUDIT_: What **proportion of patients** with dysphagia are given swallowing therapy at least 3 times a week? (the **proportion of patients** who receive the care that meets that **recommended** by the standard/guideline) _Study 2 SERVICE EVALUATION:_ How **many times a week** are patients given swallowing therapy? (primarily interested in **variation in the characteristics** of healthcare delivery) Study 3 AUDIT-CUM-SERVICE EVALUATION: What **proportion of patients** with dysphagia are given swallowing therapy **at least 3 times a week** in Consultant-led and non-Consultant-led clinics? (interested in whether **variation in patient characteristics or the characteristics of healthcare delivery** might influence whether a patient receives standard/recommended care)
34
What axis is the exposure on?
Independent → x axis
35
What axis is the outcome on?
Dependent → y axis
36
If the confidence interval around the odds ratio **does include 1**, what does this mean?
If the confidence interval includes or crosses 1, then **there is insufficient evidence to conclude that the groups are statistically significantly different** → cannot be confident there is an effect
37
Ethics vs governance?
Ethics → what is **morally** correct Governance → what has received **permission**
38
What does ethical research aim to ensure?
Ethical research aims to ensure that the **potential** **benefits** of any given study never take **precedence** over the **wellbeing** (most studies impose burdens and risks) and **rights** (most studies require informed consent) of study subjects/participants.
39
What is he role of ethics & governance approval?
aim to ensure that no human (and many animal-based) studies take place ***without ensuring appropriate measures*** are in place
40
When is ethics approval particularly important?
when the study’s participants are ***unable to consent*** e.g. dead; unconscious; unwell; lack capacity
41
Give some examples where formal ethical approval and consent may NOT be needed
The changes are **routine** and not part of the study's design and either: a) all the data used has been collected during/as an established part of a **routine practice** OR; b) the collection of any additional data does not impose **excessive burdens or risks** (though consent should be obtained)
42
What can you change without seeking further approval (a so-called ‘amendment’) from the Research Ethics Committee? ## Footnote a) Add an additional invasive measurement to the data you want to collect b) Change the content of the participant information leaflet c) Change your original hypothesis d) Recruit additional participants
Change your original hypothesis
43
What is a ‘conflict of interest’ in a study?
This refers to the situations in which **financial** or other **personal** **considerations** may compromise (or have the appearance of compromising) an investigator’s professional judgment in conducting or reporting research. ## Footnote I.e. The responsibilities of a medical researcher may be at risk of being unduly _influenced_ by a 2ary interest e.g. a **financial** **gain** or **career** **advancement**.
44
Define a public partnership
An umbrella term for describing activities which involve members of the public.
45
Define public engagement with research
Where information about research is **provided** and **disseminated** * Dissemination events * Social media * Newsletters * Websites & blogs * Creative methods
46
Define public **involvement** with research
Where members of the public are **actively** **engaged** in **shaping** and **developing** research projects
47
Define public **participation** with research
Where people **take part** in a research study
48
Define ‘coproduction' of a research project
Co-producing a research project is an approach in which **_researchers_, _practitioners_ and the _public_** work together, sharing **power and responsibility** from the start to the end of the project: * Redressing power differentials * Knowledge of equal importance * Clear roles and real responsibilities * Accessibility e.g. language
49
What is the role of NICE?
To improve outcomes for people using the NHS and other public health and social care services by: * Producing **evidence-based guidance** and advice for health, public health and social care practitioners * Developing **quality standards** and **performance metrics** for those providing and commissioning health, public health and social care services * Providing a **range of information services** for commissioners, practitioners and managers across health and social care * Reduce **variation** in the **availability and quality** of treatments and care * Help resolve **uncertainty** about which **medicines and treatments** work best and which represent best **value for money** for the NHS
50
Clinical guidelines vs quality standards?
Clinical guidelines → evidence based Quality standards → guideline based
51
What is a clinical guideline?
A comprehensive set of **recommendations** for a particular disease or condition
52
What is a quality standard?
A standard is a level of quality or attainment
53
What is the GDG (guideline developing group)?
The GDG is established by the NCC or the Internal Clinical Guidelines Programme, and is responsible for developing the clinical guideline. During development of the clinical guideline, the GDG: agrees the 'review questions' about treating and managing the condition that will guide the search for evidence.
54
What is the key role of the GDG?
**_make judgements based on evidence_**
55
Define a descriptive study
Classifies, describes, compares and measures data
56
Describe an analytical study
Focuses on cause and effect
57
Define a confounding variable
A confounder is a variable that influences both the dependent variable and independent variable, causing a spurious association
58
Define a covariate
An **independent** **variable** that can influence the outcome of a given statistical trial but is not of **direct** **interest**
59
What are the 5 different types of variable?
1. Exposure 2. Outcome 3. Mediator 4. Confounder 5. Competing exposure
60
Define a mediator
A variable that **links** the independent and dependent variable, whose existence **_explains_ the relationship** between the two variables
61
Define a confounder
A variable that influences **both the independent variable (exposure) _and_ the dependent variable (outcome)**
62
Define a competing exposure
An **ancestor** of the outcome that is not related with the exposure
63
3 list approach to classify covariates:
64
Define 1ary data collection
Data that has been **generated by the researcher (**e.g. surveys, interviews, experiments) and is specially designed for understanding and solving the research problem at hand
65
Define 2ary data collection
Data that was **formerly collected for other purposes** than that of the current research study at hand (e.g. existing data generated by healthcare providers, government institutions such as medical electronic health records, disease registries)
66
Define a prospective study
Record/measure variables _during the study period_, with the outcome subsequently measured e.g. cohort study
67
Major pros of prospective studies?
* Major strength of a prospective cohort study is the **accuracy of data collection** with regard to exposures, confounders, and outcomes and other covariates * Fewer sources of **bias** (e.g. recall or ascertainment) * Less chance of **unmeasured confounding**
68
Major cons of prospective studies?
* **Time and resource intensive** * **Expensive** * Tendency to collect data on **more variables than you need** or can use in your analyses (but not if you use a DAG) * Participants can **drop out** during a study (bias) * Usually **infeasible** for rare outcomes
69
Define a retrospective study
Record/measure the outcome and then _look back to record/measure the exposure and covariates_ e.g. case control studies and studies using existing patient records
70
What is a DAG (directed acyclic graph)?
Displays **assumptions** about the relationship between variables * Directed → Graph has a direction (topological ordering) * Acyclic → A graph without cycles (a cycle is a complete circuit), so you will never visit the same node twice
71
Pros of using newly collected data over existing data?
Helps ensure that you **record all the variables** you need, using the **best techniques** available, applied consistently
72
Cons of using newly collected data over existing data?
* More expensive & time consuming * Harden to recruit participants * Usually constitutes ‘research’ – therefore requires **ethical approval**
73
Pros of using existing data over newly collected?
Less expensive & less time consuming
74
Cons of using existing data over newly collected?
* Limited choice as to which variables have been measured * Limited involvement in the (in)consistency of measurement * Limited involvement in the level of ‘missingness’ tolerated
75
Define a registry
A collection of information about individuals, usually focused around a specific diagnosis or condition.
76
Define a measurement error
The difference between the measured value of a variable and its true value.
77
Define response bias
A general term for a wide range of tendencies for participants to respond inaccurately or falsely to questions (i.e. what interviewer wants/gets)
78
Define prestige bias
A bias towards copying ‘prestigious’ individuals (i.e. what appears favourable)
79
Define recall bias
Participants are systematically more or less likely to recall and relate information on exposure **depending on their outcome** (prospective/retrospective)
80
Define a proxy
A variable that is not in itself directly relevant but serves in place of an unobservable or immeasurable variable. E.g. intended variable = true body fat percentage, proxy variable = BMI
81
Define a latent variable
A variable that cannot be observed but can be detected by their effects on variables that are observable.
82
Define a sample
A sample is a subset of your population by which you select to be participants in your study.
83
Define sampling
The process of selecting a **subset of a population** which will be a **representation** of the **whole population**.
84
Define a target population
The **total**, **finite** population of people/contexts (to whom we wish to _apply_ our study’s results and from which any study sample is drawn).
85
What should sampling ensure?
Sampling should ensure that the sample is a **true representative** of the population.
86
Probability sampling is a sampling technique, in which the subjects of the population get an **equal** **opportunity** to be selected as a representative sample. Non-probability sampling → the elements that make up the sample are selected by **nonrandom methods**
87
What is sampling bias?
This involves problems in your sampling, which reveals that your sample is **not representative** of your population.
88
Most important source of sampling bias?
Most important are those arising from your **inclusion/exclusion criteria**.
89
What is a stratified random sample?
* The whole population is divided into **homogeneous strata or subgroups** according to a **_demographic factor_** (e.g. gender, age group, religion, socio-economic level, education, or diagnosis etc.) * **Randomly sample** from the target population within strata (particularly to ensure equal numbers by exposure and confounder status) * Every member of the target population within each stratum has the **same chance/probability** of being sampled * The numbers in each stratum can be **oversampled** to strengthen analysis
90
Pros of stratified random probability sampling?
* Representative of population * Unequal sampling of strata improves power for rare strata
91
How can you achieve a random/probability sample?
We use a *systematic approach* designed to ensure that every person/context in the ‘target population’ has *an equal chance/probability* of being included in the ‘study sample’ Methods: * Table random numbers * Computer generated list of random numbers * Lottery methods
92
What is the purpose of a sample size calculation?
to ensure that your study is **large enough** to have a good chance of detecting any effect you hope to see
93
What does it mean if the confidence interval around the odds radio does not include one?
confident that the effect is **genuine**
94
How can you improve the chances that the confidence interval doesn't include 1?
**_increase the sample size_** (a **bigger sample** to estimate from will make the estimate more **accurate** with less **variability**).
95
In which evaluation study activities can it be helpful to consult clinical and non-clinical stakeholders?
1. Design of the research 2. Development of the grant application (pre-protocol work) 3. Undertaking/management of the research 4. Analysis of data 5. Dissemination of research findings

Yr 3 - RESS3 (5 decks)

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