Research Flashcards
The basic objective of research is to acquire _______
new knowledge and justification for decision making in
medical practice
______ refers to the ‘true’ answer, which must
be relevant, complete and accurate
Validity
Three significant questions that evaluate validity are:
• Is the study useful or is the result inconclusive?
• Do you accept the results of this study as applied
to the source population?
• Do the results apply to the population in which
you would be interested?
________ refers to the adequacy of the
study methods in reference to the study population
Internal validity
_________refers to the generalisability of
the results to the general population
external validity
______ refers to the stability of question-andanswer
response and is most successfully measured
by testing and then retesting (repeatedly).
Reliability
The most frequently used method of testing for __________is to repeat application of the test.
repeatability
_______ and _______, which are integral to
validity, are important considerations in decision
making in medicine, particularly in choosing
appropriate investigations for disease diagnoses
Sensitivity and specificity
The_______ of a test depends on the proportion
of people with the characteristic (disease) in whom
the test is positive
sensitivity
_____ is (i.e. percentage positive with disease).
Sn
The________of a test depends on the proportion
of people without the characteristic (disease) in
whom the test is negative (i.e. percentage negative
of healthy people).
specificity
The ultimate specific test is one
that detects all the_____
truly negative (disease-free) cases
A _____test is one that is as close to 100%
specificity and 100% sensitivity as possible.
gold standard
Predictive values that are useful indices of validity
can be expressed as ______ and _____
positive and negative values
______ refers to the number of new cases of a disease (or factor of interest) occurring in a defined population within a specified period of time.
Incidence
______ refers to the total number of
individuals who have the disease (or factor of
interest) at a particular time in a population. Thenumber is divided by the number of people in the population at that time
Prevalence
This is any effect occurring during the investigation that tends to produce results that depart systematically from the true values
Bias
types of bias
1.
2.
3.
- measurement bias (
- confounding bias
- selection bias
This is a situation in which a measure of the effect of exposure on risk is distorted by the association of exposure with other (known or unknown) factors that influence the outcome
Confounding
A ______ is a factor that distorts the apparent magnitude of the effect of
a study on risk.
confounder
The reasoning process of the researcher is based on the ________that is, an experimental group does not differ from a control ‘normal’ group in outcome.
null hypothesis
Two basic components of subject selection are ______ and _______ The latter should
be selected in a well-controlled manner
sample size and sample representativeness.
A useful rule is to aim to approach
_______patients if you wish to work with a sample size of n .
3n
The two broad categories of research in general practice are _______research, which is based on observation and talking with people, and ____ research, which is based on measurement and analysis
of data collection
qualitative
quantitative
Research can also be classified as _____ research, which includes both qualitative and quantitative methods, and _____research, which involves
systematic reviews and meta-analysis.
primary
secondary
This research is basically concerned with evaluating human behaviour from the subject’s perspective.
It is based on close observation and is expressed in a descriptive way.
Qualitative research
Qualitative approaches to research 1 2 3 4
- Phenomenology
- Ethnography
- Grounded theory
- Biography (life story, narrative enquiry)
- Case study
Methods used in qualitative research
- interviews (open-ended, semi-structured)
- focus groups
- participation observation
- document analysis
What type of research
The central focus of philosophy/method is the lived experience of the world of everyday life
Phenomenology
What type of research
• effects of Viagra (and other agents) on marital/
sexual relationships
• experience of carers in Alzheimer disease
• effects of workplace bullying on absenteeism
Phenomenology
This examines cultures, peoples and societies
including subgroups, e.g. adolescents. It is the basis of anthropology.
The investigator usually identifies one
or more key witnesses (informants) and interviews them to clarify observations.
Ethnography
This is the development of new theory through the collection and analysis of data. It seeks to identify the core social processes within a given context in order
to build theory that is grounded in the reality of those being studied
Grounded theory
_____is research based on the collection of data in numerical quantities and asks a specific narrow question, such as ‘What is the chance that . . .?’ or ‘What proportion of . . .?’
Quantitative research
Quantitative research:
It can be classified broadly as _____ which includes case control, cross-sectional and cohort studies, and ____
which includes the classic controlled trial
observational,
experimental,
is an observational study in which people with a disease (cases) are compared with those without it (control group).
Case control (or retrospective) stud
What type of research?
Patients with mesothelioma
were investigated for exposure to asbestos or other agents;
_________follows a correlation approach using existing databases.
It is a survey of the frequency of disease, risk
factors or other characteristics in a defined
population at one particular time
Cross-sectional or prevalence study
What type of study?
The prevalence of diabetes mellitus (diagnosed and undiagnosed) was investigated in an Aboriginal community living in a particular area of metropolitan Sydney.
Cross-sectional or prevalence study
_______ is also referred to as ‘follow-up’. The study follows a group (cohort) of individuals with a specified characteristic or disease over a period of time.
Comparisons may be made with a control group
Cohort (or prospective) study
What type of research?
120 patients with chronic sciatica
were followed over 10 years to determine
the outcome of their pain and neurological
deficit. These were compared with a matched
group who had undergone laminectomy
______ is an experimental
study that tests for hypothesised outcomes.
An intervention is conducted on a randomly
selected group of people and compared with a matched control group not subject to the specific intervention.
Clinical controlled trial
What is the objective of a Clinical controlled trial?
The objective is to establish a
causal relationship between the intervention and the hypothesised outcome
The ideal scientific
trial is a ______ where neither staff
nor the participating patient are aware the
participant is in the intervention or control
group.
double-blind trial
______ is the process that systematically assesses compatible randomised controlled trials by merging the data (from usually smaller and
inconclusive trials) to draw a ‘firmer’ conclusion from
larger numbers of subjects
Meta-analysis
___________) is a process of basing clinical practice on validated information
Evidence-based medicine (EBM
_______is the integration of the best available scientific evidence with your clinical expertise and knowledge, your intuition, your wisdom’.
EBM
Steps for EBM
The proposed five steps of EBM are similar to
basic research methodology: 14
1 Construct a clinical question or define the
problem.
2 Search for the evidence.
3 Appraise the quality and relevance of the
evidence.
4 Apply it to the care of an individual patient.
5 Evaluate how effective it is.
What level of evidence?
Evidence obtained from a systematic review of all relevant randomised trials
1
What level of evidence?
Evidence obtained from at least one properly
designed randomised controlled trial.
2
What level of evidence?
Evidence from well-controlled trials that are not randomised, or well-designed cohort or case-control studies, or multiple time series (with and without the
intervention).
3
What level of evidence?
Opinions of respected authorities; based on clinical experience; descriptive studies; or reports of expert
committees.
4
What is the strength of EBM
The strength of EBM is that it can provide the
answers to very important everyday decisions,
especially in screening and preventive medicine, where
guidelines have fluctuated over the decades
The absolute difference in event rates between two intervention or treatment
groups. It gives an indication of the baseline risk and treatment effect.
ARR
What does an ARR of 0 mean?
An ARR of 0 means no difference and
thus the treatment has no effect
A UK journal on EBM with excellent summaries on NNT for a host of common interventions
Bandolier: www.medicine.ox.ac.uk/bandolier/
This allows comparisons between
the means of two samples of similar populations with a normal distribution.
Analysis of variance
The statistically derived range of
values around a trial result in which the probability is that the true result will be within the range.
Confidence interval
It is a measure of the
certainty that the figures are correct
Confidence interval
_________ The percentage of subjects
in the control group that experienced the event of interest.
Control event rate (CER)
_______The percentage of subjects in the intervention group that experienced the
event of interest
Experimental event rate (EER)
measures the agreement between
the evaluations of two raters when both are rating the same object.
A value of 1 indicates perfect agreement.
A value of 0 indicates that agreement is no better than chance.
Cohen’s kappa
The number of people who must be treated over a given period of time with
the experimental therapy (specific intervention) to achieve one good outcome or prevent one adverse
outcome.
NNT
T or F
the lower the NNT, the better the treatment
T
How to compute NNT
It is calculated as 100/ ARR (%); that is, the reciprocal of
the ARR.
T or F
The NNT will be different for different patient
populations depending on their baseline risk for developing the outcome of interest
T
The probability of the occurrence of an
event to its non-occurrence
Odds ratio
The probability that an observed
difference occurred by chance.
P value
What is the standard convention for obtainiing P value?
The standard
convention is that there is only a 5% (1 in 20)
probability that the difference would fall outside this
range by chance alone (i.e. a P value of 0.05 or 5%).
The ratio of the risk of the outcome
(e.g. disease or death) in the treatment/exposure group compared with the control/unexposed group
Relative risk (RR)
How to compute RR
RR = EER / CER
How to interpret RR
RR = 1 means no difference, so treatment has no
effect
RR > 1 means the treatment increases the risk of
disease/death
RR < 1 means the treatment decreases the risk
The proportional reduction
of adverse events between the treatment/experimental
and the control groups in a trial`
Relative risk reduction (RRR)
How to compute RRR
RRR is the ratio of the absolute risk reduction to the risk of the outcome in
the control group)
An alternative way to calculate the
RRR _____
is to subtract the RR from 1 (i.e. RRR = 1 - RR ).
_______ is probably the most commonly reported measure of treatment effects but the _____ gives a more realistic
picture
RRR
ARR
_____ The probability that an event (death or disease) will occur.
Risk (R)
_______The likelihood of a difference
between two groups being real.
It is the possibility that the difference occurred by chance alone.
Statistical significance
_____error occurs when a study
concludes that there is a difference between two groups when there is no difference
A type I
occurs when a study
concludes that no difference exists between groups
when there is a true difference
Type II error
Questions to ask in critical appraisal
1 What were the objectives of the study?
2 Were the ethical aspects properly followed?
3 What was the study design?
4 Were there any potential problems associated
with the design
Questions to ask in critical appraisal
5 Were all the patients who entered the study
properly accounted for at its conclusion?
6 What were the important results?
7 How would you interpret and explain these
results?
