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HaDPop > 3 survey > Flashcards

3 survey Flashcards

1
Q

Survey = an investigation in which …1… is ….2…. but in which …3… is not used

A
  1. information
  2. systematically collected
  3. experimental method
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2
Q

What does it mean by when the information of a survey is systematically collected ?

A

observing, not manipulating

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3
Q

How may a survey be conducted ?

A
  • face-to-faceinquiry
  • self-completed questionnaires
  • telephone
  • postal service
  • or in some other way.
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4
Q

Generalizability of results depend on…

A

Extent to which surveyed population (sample) is representative

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5
Q

what are prevalence studies also called ?

A

cross-sectional studies

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6
Q

4 examples of health-related surveys

A

1) Face-to-face structured interview & measurements
2) Self-completed non-motor questionnaire for Parkinsonism
3) ONS Coronavirus Prevalence Survey: self-swab PCR
4) Child Development Supplement: parent-reported weight/height

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7
Q

The purpose of surveys

A
  • Assess prevalence of disease (cross-sectional survey)
  • Measure risk/protective factors of respondent
  • Measure outcomes
  • Ad-hoc data collection = collect information of interest
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8
Q

which studies is a frequently taken form of a survey ?

A

prevalence

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9
Q

3 advantages of prevalence studies ?

A
  • cheap and quick
  • useful for healthcare planning and investigating trends over time
  • useful when routine data not available
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10
Q

3 disadvantages of prevalence studies

A
  • not (usually) useful for conditions with a short duration (P = I xD)
  • not particularly useful for investigating causality
  • sampling and data collection need care
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11
Q

define population

A

the group of people in whom we are interested in and wish to apply the results of the survey to

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12
Q

define Sample

A

group of individuals taken from larger population

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13
Q

A value calculated from a sample is a ….?

A

statistic

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14
Q

A statistic is always what ?

A

an estimate of the true underlying value in the population

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15
Q

Aim of sampling is to ?

A

generalise findings from sample to the population

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16
Q

sampling is used to make inferences from sample results to population,

the sample must be ..1…. of the population ?

A
  1. representative
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17
Q

What is a sampling frame? give an example

A

list of everyone in the population from whole sample taken

e.g. GP practice list, electoral register, school register, employee register

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18
Q

With sample size, generally the ….1…. the sample size, the better

A
  1. larger
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19
Q

What are the 2 different sampling methods ?

A
  • random (probability)
  • non-random (non-probability)
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20
Q

In random sampling:
everyone in the ….1… frame has an ..2… probability of being chosen
it’s important to achieve a …3…. sample

A
  1. sampling
  2. equal
  3. representative
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21
Q

Non-random sampling:
* …1… and ….2…..
* unlikely to be ….3….
* beware of …..4…. samples

A
  1. easier
  2. convenient
  3. representative
  4. self-selecting
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22
Q

name 4 random sampling methods

A
  • simple random
  • stratified
  • cluster
  • systematic sampling (not truly random)
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23
Q

what is simple random sampling ?

A

each population member given an identifier and numbers selected at random

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24
Q

what is stratified sampling ?

A

Divide population into strata (subgroups) and select sample from each using simple random sampling

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25
Q

what is cluster sampling ?

A
  • Use natural ‘clusters’ in the population e.g. schools.
  • Simple random sample of ‘clusters’ (e.g. schools).
  • Study all individuals within clusters
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26
Q

what is systemic sampling?

A

Every Nth population member selected

27
Q

Methodological design can be influenced by two factors - what are they?

A

1) Choice of instrument e.g., interview vs. self-reported questionnaire
2) Quality control = standardisation of instruments, training of the interviewers, structured questionnaires

28
Q

What is the pros and cons of using an INTERVIEW as the choice of instrument?

A

Pros
- Allows for open questions
- Ensures questions are understood
- Can explore questions in depth

Cons
- Can be timely/costly
- Requires training
- Includes interviewer bias

29
Q

What is the pros and cons of using an SELF-COMPLETED QUESTIONNAIRE as the choice of instrument?

A

Pros
- Quick & cheap
- Avoids interviewer bias
- Good for sensitive issues

Cons
- Relies on more closed questions = risk of being misunderstood

30
Q

Name some examples of how quality control of methodological design is maintained?

A

1) Standardisation of instruments used
2) Training for interviewers/observers
3) Structured questionnaires

31
Q

Name some ways in which questionnaire design of a study (survey) can be strengthened

A

1) Avoid crowding questions - ensure clear, logical flow
2) Order questions appropriately (sensitive questions later)
3) Avoid leading questions
4) Avoid ambiguity (double-barrel questions)
5) Search for validated measures in literature
6) closed vs open questions
7) pilot to test acceptability of length of questionnaire

32
Q

How to avoid instrument bias when measuring instrument performance ?

A

assessing (measuring) how well the test, instrument or question performs; over time, in different settings, with different groups

33
Q

what are the 2 key components of measurement performance ?

A
  1. validity
  2. repeatability (or reliability or reproducibility)
34
Q

What is validity ?

A

how well a test measures what it is claimed to measure (the capacity of a test to give a true result)

35
Q

repeatability (or reliability or reproducibility) = degree to which …?

A

a measurement made on one occasion agrees with the same measurement on a subsequent occasion

36
Q

Why are estimates obtained from a sample ?

A

to make inferences about real e.g. prevalence (or real risk or real incidence etc.) in the population of interest

37
Q

the error that occurs in estimating the true effect is either …1… or ….2…

A
  1. random
  2. systemic
38
Q

what is a random error ?

A

a random imprecision or variable performance that is due to chance alone

39
Q

what is a bias ?

A

a systematic error in sampling or measurement

40
Q

Examples of systemic error (sources of bias) : ?

A
  • selection bias: sampling bias, non-response bias
  • information (measurement) bias: instrument bias, inter-observer bias
41
Q

what is a selection bias ? error due to systematic differences in ….

A

in the characteristics of the groups being studied due to differences in the way they were selected

42
Q

2 types of selection bias

A
  1. sampling bias -> non-representative sampling
  2. non-response bias -> respondents differ from non-responders
43
Q

2 examples of sources of bias (systemic error)

A
  1. selection bias
  2. information (measurement) bias
44
Q

what is information (measurement ) bias ? error due to systematic differences in ….

A

the measurement or classification of individuals in the groups being studied

45
Q

2 types of information bias ?

A
  • instrument bias
  • inter-observer bias
46
Q

Instrument bias = systematic error due to ….. ?

A
  • inadequate design,
  • calibration
  • or maintenance of instruments
47
Q

Inter-Observer bias = systemic error between ….. e.g. due to training

A

measurements of different interviewers

48
Q

Measurement errors can be due to issues in …… and …..

A

precision, accuracy

49
Q

If there is lots of variation (random error) - precision is …..1…..
If there is little random variation - measures are …2…

A
  1. poor
  2. precise
50
Q

what is accuracy ?

A

how close the average measurement is to the true value

51
Q

What is poor accuracy the result of ?

A

systemic error (bias)

52
Q

How could we minimise sampling bias in surveys ?

A

random sampling

53
Q

How could we minimise non-response bias in surveys?

A

Cover letter signed by the respected person - explaining the reason and relevance of the survey.

Ensure language spoken is appropriate.

Provide reminders and incentives.

54
Q

How could we minimise instrument bias in surveys?

A

Good design of questionnaires, calibration and maintenance of equipment.

55
Q

How could we minimise interviewer bias in surveys?

A

Training, objective criteria for outcome assessment, closed questions.

56
Q

what is response rate ?

A

% of selected sample that take part in suvery / study

57
Q

How can we check for non-response bias?

A

Compare the respondents’ characteristics with the non-respondents’ characteristics

58
Q

If data on non-respondents’ not always available what do do ?

A

make external comparisons with wider population of interest

59
Q

4 methods to check how representative a sample is

A
  1. response rate
  2. compare respondents’ characteristics with non-respondents’
  3. make external comparisons with wider population of interest
  4. present data in a table
60
Q

When critiquing literature , what 3 questions should be considered broadly ?

A
  • What are the conclusions?
  • What is the strength of the evidence?
  • Does the methodology give you confidence in the conclusions?
61
Q

In critical appraisal if the question is
Was there a clear statement of the aims of the research?

what are 3 considerations ?

A
  • What was the goal of the research?
  • Why it was thought important
  • Its relevance
62
Q

In critical appraisal if the question is

Was the research design appropriate to address the aims of the research?

considerations ….?

A

If the researcher has justified the research design (e.g. have they discussed how they decided which method to use)?

63
Q

In critical appraisal if the question is

Was the recruitment strategy appropriate to the aims of the research?

considerations ….?

A
  • If the researcher has explained how the participants were selected?
  • If they explained why the participants they selected were the most appropriate to provide access to the type of knowledge sought by the study?
  • If there are any discussions around recruitment (e.g. why some people chose not to take part)?

HaDPop (13 decks)

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