2 Res Design

7/28/2019 2 Res Design

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Research Design Dr. Shabbir Khan

MBA, PGDT&D,BGL, CFET,PGDIT, CDM, CCM, BEd, Med, MPhil, PhD


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Meaning of research design The arrangement of conditions for

collection and analysis of data in amanner that aims to combinerelevance to the research purpose witheconomy in procedure


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Need for research design Smooth sailing of various research operations Yielding maximal information Minimal expenditure of effort, time & money Plan for house Advance planning of methods to be adopted forcollecting relevant data and techniques to be used inanalysisEfficient and appropriate design must be Preparedbefore starting research operation OR futile

Organize ideas in a form Possible to look for flaws & inadequacies Need for providing comprehensive review


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Features of good research design Flexible Appropriate Efficient Economical Minimises bias

Maximises the reliability of collected data and analysed A research design should consider, - Means of obtaining information - Objective of the problem to be studied - Nature of the problem to be studied - Availability of time and money Emphasis on discovery of ideas and insights Hypothesis if casual relationship b/w variables


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Studydesigns

Analytical

Cohort

Experimental

RCT Non-RCT

Observational

Casereport

Descriptive

Caseseries

Cross-sectionalstudy

Case controlstudy

Cohort

Different research designs


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Case report Studies describing the characteristics of

a single patient


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Case report-merits Record unusual medical occurrences and can Give the

first clues in identification of a new disease or adverse

effects of an exposure Only means of surveillance for rare clinical events Serve to elucidate the mechanism of disease and

treatment


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Case report-Demerits Cannot be used to test for the presence

of valid statistical association because it isbased on the experience of one person


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Case Series

Studies describing the characteristics of a groupof patients with similar diagnosis Collection of 5 & more cases


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Case series-merits

Helps in formulating a useful hypothesis regarding risk factors of disease or identifying

a new disease or outcome of new treatment Informative for very rare disease with few established risk

factors May suggest the emergence of a new disease

or epidemic


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Case series-De merits

Cannot be used to test for the presence of valid statistical association due to absence of a comparison group


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Cross-sectional studies-Merits Provide information about the frequency of an

attribute and potential risk factors Helps to generate a hypothesis Can give a good picture about the health care needs of

the population at the point of time Can be used to investigate multiple exposure and multiple

outcome Suitable for chronic cases


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Cross-sectional studies-Demerits Difficult to establish the time of sequence of

events They are not suitable to investigate rare

diseases, rare exposure or disease of short duration Being based on prevalent rather than incident

cases Limited value to investigate etiological

relationship


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Case control study Type of analytical study By observation and analysis Retrospective evaluation to determine who

was exposed and who was not exposed

retrospective study To examine the possible relation of anexposure to certain disease

- Identify the individual having the disease case


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Individual dont have the disease comparisonpurpose

individuals withdisease TIME Direction of enquiry

Absent individuals w/odisease


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Cohort study Forward looking study Prospective study Incidence study Longitudinal study

There is regular follow up over a period of time Factor (s)

Individuals exposed Present TIME Direction of enquiry

individuals unexposed Absent


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Cohort study Elements of a cohort study, 1. Selection of study subjects

2. Obtaining data on exposure 3. Selection of comparison group 4. Follow-up

Incidence can be calculated Examines multiple effects of a single exposure Provides direct estimate of relative risk Minimizes bias Dose-response ratios can be calculated Elucidates temporal relationship b/w exposure & disease Inefficient for rare diseases

Expensive and time consuming Involves large sample size Alters people behaviour Changes in standard methods or diagnostic criteria of disease over prolongedfollow-up

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