Research methodology

contentsIntroduction to researchDefinitions

ResearchThesisDissertation

Why to do a researchCategories of researchResearch methods & research methodologyProcedural steps in researchResearch strategy epidemiologic studiesEthics in research

Introduction

Investigation using scientific procedures, by searching again and again to find out the truth

Research is the continual search for truth using the scientific method. It is the pursuit of the truth with the help of study, investigation, observation, comparison and/or experimentation.

definitions

Research (WHO Health research methodology, 1992, a guide for training in research methods):

Research is a quest for knowledge through diligent search or

investigation or experimentation aimed at the discovery and

interpretation of new knowledge. Scientific method is a

systematic body of procedures and techniques applied in

carrying out investigation or experimentation targeted at

obtaining new knowledge. Here research and scientific

methods may be considered a course of critical enquiry leading

to discovery of facts or information which increases our

understanding of human health and disease.

Thesis

(according to Oxford English dictionary)

A proposition laid down as a theme to be

discussed and proved. A discussion to

maintain and prove a thesis especially

written or delivered by a candidate for

university degree- Ph.D

Dissertation:

• Dissertation means “to discuss”.

• It is an academic activity laid down by the university for the

partial fulfillment of MDS degree.

• It is an exercise to train a PG student to plan, execute, evaluate,

write and report a scientific project.

• It is an in-depth study of a particular topic which contributes new

information and knowledge in the field

• A formal, often lengthy treatise (a book or writing of some

particular subject, one containing a methodical discussion or

exposition of principles of subject) or discourse, especially one

written by a candidate for a master’s degree.

It is a pre-requisite or academic activity for acquiring a masters degree or doctorial.

To find out the truth which is hidden and which has not been discovered yet.

To contribute new knowledge to the existing one as the scientific knowledge develops in increments.

As a profession to conduct research in various aspects.

To solve an existing health problem.

For thrill and enjoyment of discovering a new fact.

Categories of research

Empirical research and theoretical research

Basic research and Applied research Empirical

Observational research

Experimental research

Basic or pure research

It is usually considered to involve the search for knowledge without a defined goal of utility or specific purpose.

Eg. The microbiologist, whose expertise is the identification of pathogenic micro organisms may conduct research in-vitro, in a laboratory on bacterial reproduction, growth and endotoxin production without any direct application to clinical dentistry. Probably, the researcher is interested in monitoring endotoxins produced over the life cycle of bacteria to determine a pathogenecity.

Applied research

It is problem oriented and is directed towards a defined and purposeful end.

Eg. An oral health researcher investigating the relationship between periodontal disease and myocardial infarction may use the findings of the microbiologist as a theoretical framework to test the relationship between bacterial endotoxins, periodontal disease and myocardial infarction in animal and then in human subjects

Research methods

methods/ techniques that are used for conducting research are termed as research methods or research techniques.

They fall into 3 groups

1. Those concerned with collection of data

2. Those statistical techniques which are used for establishing relationship between the data and the unknown

3. Those methods which are used to evaluate the accuracy of the results obtained.

identify problemLiteratur

e reviewPlan research

design

Determining sample

size

Write protocol

Ethical committee approval

Pilot study and main

study

Presentation &analysis of results

Hypothesis testing

Generalisation interpretation

Report writing

publication

Pr

oced

ural

ste

ps in

rese

arch

Selection of problem for investigation-further exploration Inexperienced-seek opinion –senior Constructing –essential starting point

Review literature Modern electronic research Abstract collection held on CD-ROMS-enables –key words Medline and psyclit database Role of systemic review grown recently-cochrane

collaboration-reviews from volunteer researchers internationally adds them to a bank,which is open for inspection by interesting parties.

Specifying study design

Selection of measures: many measure ,assessments Eg:self report rating scales for dental

anxiety,observations,interviews,stand questionnaires simple rating scale can be given a no.1-strongly agree 2-agree 3-undecided 4-disagree 5-strongly disgree May not exist for the study ,this may necessiate the

development of new scale. should possess Reliability and validity

Selection of sample: Sampling techniques-inorder to provide information ,can be generalised

to cover the whole population.

Writing a protocol: aims & objectives,method,materials,sample ,procedure

Ethical approval Pilot work Main study Analysis of results Report writing publication

Research strategies

Selection of a research strategy is the core of a research design and is probably the single most Important decision the investigator has to make, i.e. whether to undertake a descriptive, an analytical or an experimental study.

Classification of Epidemiologic studies

Observational studies

Descriptive studiesSurveys

(questionnaire or others)

Case studies

Correlational studies

Analytical studies

Ecological or correlational

studies

Cross-sectional or prevalence

studies

Case-control or case-

reference studies

Cohort or follow-up studies

Experimental or intervention studies

Randomised

controlled trials or clinical trials

Field trials or

community

intervention studies

Community trials

Decscriptive study

Concerned with observing the distribution of disease or health related characteristics in human population

Eg. Surveys. Defining population:denominator Defining the disease:operational definition. Describing disease-time,place and personTime: Short term fluctuation:

1. Common source epidemics-single,continuous2. Propagated epidemics-person to person transmission of

infectious agent---epidemics of hepatitis A and poliomyelitis3. Slow or modern epidemics

Periodic fluctuations: Seasonal –communicable diseases like

measles,varicella,malariaEg:upper Resp tract infections inc during winter and GI inf in

summer Cyclic trends-measles-incidence every 2-3 yrs Influenza occurs at intervals of 7-10 yrsLong term fluctuation Changes occur over long period of time,change in frequency

encompassing sev decadesEg:CHD,diabetes,lung cancer shows upward trend in 50 decades

and TB, typhoid downward

Place distribution:Interanational-National-endemic disease like goitre,flourosisRural-urban-lung cancer,cardiovascular accidents-urbanLocal-spot maps (john snow –on epidemic of cholera)and shaded

maps -study

Person distribution:age sex Measurement of disease :morbidity and mortality indicators

Expressed in terms of incidence and prevalence Comparing with known indices:comparision b/n different

population and subgroups of same populn-clue to etiology Formulation of hypothesis:relating to disease etiology specify-population,sp cause ,expected outcome,dose-

response r/n,time-resp r/n.Eg:smoking of 30-40 cigarettes/day causes lung cancer in

10% of smokers after 20 yrs of exposure.Uses:1. magnitude and type of disease in community2. Clues to etiology3. contributes to research

surveys

Surveys are methods of scientific or systematic collection of data, compiling, presenting in order (useful manner), analysing and evaluating them

The focus of attention must be on the followinga) Formulating the objective of the study-obj describing

what is to be measured,resources

b) Designing the method of data collection eg. Questionnaires, interviewing, examination of records or observations

c) Selecting the sample

Conducting examination:1. Obtaining approval from authorities2. Budgeting3. Scheduling4. Emergency care and refferal5. (diagnostic method)Validity and reliabilty of the data

Classification of study types-ADA(1970)typeI: complete examinationtypeII: limited examinationType III: inspectionType IV:screening procedures:tongue depressor

d) Analysing the datae)Drawing the conclusionf) Publishing the reports

Case study: it is an intensive investigation of a person, a family, a group, a social institution or an entire community in a natural setting

Correlational study: it is a descriptive research technique utilized to identify consistent relationship among variables

Analytical study

Second major typeSubject of interest –individual with in populationObject –not to formulate but test hypothesis

Can determine:1.Statistical association between disease and

suspected factors2.If exists--strength

Case control studies Design of a case-control study

Time

Direction of enquiry

Exposed

Not Exposed

Cases

Not Exposed

Exposed

Controls

Population

Defining the cases and controls: Case: you have to decide a case before the start

of the study. The case has to fit in to two criteria.

1. Diagnostic criteria.

2. Eligibility criteria. only newly diagnosed cases within a specified

period of time than old cases

Selection of cases

The criteria for inclusion in the study must be clearly specified.

Sources of cases:

▪ Hospitals

▪ General population

Controls they must be as similar to the cases as possible, except for

the absence of the disease,which is under study.

Selection of controls Crucial step in case-control studies

Controls must be

▪ Be similar to the cases except for the absence of the disease under study

▪ Equal ratio

Sources of controls Hospitals:diff illness

Relatives

Neighborhood controls

General population

Matching

Definition:

the process by which we select controls in such a way that they are similar to cases with regard to certain pertinent selected variables, which are known to influence the out come of disease and which, if not adequately matched for comparability, could distort or confound the results.

Example: age.

Confounding factor One which is associated both with exposure and disease; and is

distributed unequally in study and control groups Although associated with ‘exposure’ under investigation, it itself

is a risk factor for the disease

Measurement of exposure Exposure can be measured by

Interviews Questionnaires By studying past records Examinations

Bias/ systematic error should be avoided while measuring the exposure

Analysis Involves two steps1. Exposure rates among cases and controls2. Estimation of disease risk associated with

exposure (odds ratio)

1. Exposure rates

cases controls

Smokers

33(a)

55(b)

non Smokers

2( c )

27(d)

Total 35(a+c)

82(b+d)

Exposure rate among cases= (a/a+c)100 = (33/35) 100 = 94.2 %

Exposure rate among controls= (b/b+d)100 = (55/82) 100 = 67 %

A case control study of smoking and lung cancer

2.Estimation of risk

Cases Controls

Smokers 33(a)

55(b)

Non smokers

2( c )

27(d)

Total 35(a+c)

82(b+d)

= a/(a+b) / c/(c+d)Relative risk =

Incidence among non exposed Incidence among exposed

Relative risk (RR) or Risk ratio

Odds ratio (cross product ratio)

It is a key parameter in the analysis of case control studies

A measure of the strength of the association between risk factor and outcome

Derivation of odds ratio is based on 3 assumptions

Disease under investigation is a rare one Cases are representative of those with disease Controls are representative of those without

disease

Odds ratio = ad/bc = 33 X27/ 55X2 = 8.1

Smokers have a risk of having lung cancer 8.1 times that of non smokers

cases controls

smokers 33(a)

55(b)

Non smokers 2( c )

27(d)

total 35(a+c)

82(b+d)

Bias in case control study1. Bias due to confounding2. Memory bias3. Selection bias4. Berksonians bias:different rates of admission to

hosp for people with diff disease5. Interviewer’s bias

advantages of …

Relatively easy to carry out Rapid and inexpensive (compared with cohort studies) Require comparatively few subjects suitable to investigate rare diseases or diseases

about which little is known. No risk to subjects Allows the study of several different aetiological factors (e.g.,

smoking, physical activity and personality characteristics in

myocardial infarction) No attrition problems, because case control studies do not

require follow-up of individuals into the future Ethical problems minimal

Disadvantages of … High chances for bias

Validation of information obtained is difficult or sometimes impossible

Selection of an appropriate control group may be difficult

We cannot measure incidence, and can only estimate the odds ratio but not relative risk

Not suited to the evaluation of therapy or prophylaxis of a disease

Another major concern is the representativeness of cases and controls

Cohort studies

Usually undertaken to obtain additional evidence to refute or support the existence of an association

between suspected cause and diseaseOther names

Incidence study

Forward looking study

Longitudinal study

Prospective study

distinguishing Features of …

Cohorts are identified prior to the appearance of

the disease under investigation

Study groups are observed over a period of time

to determine the frequency of disease

The study proceeds from cause to effect

Cohort is defined as a group of people who share

a common characteristic or experience within a

defined time period

Eg, birth cohort,age cohorts, occupational

cohorts, exposure to a drug cohorts, marriage

cohort etc.

The comparison group may be…

the general population from which the cohort is

drawn

Indications for …

When there is a good evidence of an

association between exposure and disease

When the exposure is rare but the incidence

of disease is high among exposed

When the attrition can be minimised

When ample funds are available

Design of a cohort study

Population free of

condition

Screening to exclude those with the condition

SAMPLE

With the characteristic

Without the characteristic

Time

DevelopDisease

Do not develop disease

DevelopDisease

Do not develop disease

Time

Direction of enquiry

a

b

c

d

Considerations for selecting cohorts

Cohorts must be free from the disease under study

both the groups should be equally susceptible to disease under study

Both the groups should be comparable in respect of all possible variables, except the assumed risk factors

Diagnostic and eligibility criteria of the disease must be defined beforehand.

Inclusion and exclusion criteria should be clearly stated before the commencement

Steps in …

Selection of study subjects

Obtaining data on exposure

Selection of comparison groups

Follow up

Analysis

Selection of study subjects

Cohorts can be selected from

General population

Special groups

▪ Select groups (eg. Doctors, lawyers, teachers, etc.)

▪ Exposure groups

Obtaining data on exposure

Information can be obtained from

Cohorts

Review of records

Medical examination or special tests

Environmental surveys

Information about exposure should facilitate

classification of cohort members

According to whether or not they were exposed

According to the degree of exposure

Selection of comparison groups

Internal comparisons: no outside comparision group is required

External comparisons: when degree of exposure is not available,ext

cohort .eg:smokers and non smokers,radiologists and opthamologists.

Comparison with general population:mortality experience of exposure group is

compared with mortality experience of general populationin same geographic area

Follow up

Periodic medical examination of each member

Reviewing physician and hospital records

Routine surveillence of morbidity and mortality

records

Mailed questionnaires, telephone interviews,

periodic home visits

Analysis

Data is analysed interms of

i. Incidence rates of outcome among exposed and non-exposed

ii. Estimation of risk

▪ Relative risk

▪ Attributable risk

Incidence rates

Incidence can be

measured directly

Incidence rate among

smokers = 70/7000 =

10 per thousand

Incidence rate among

non-smokers= 3/3000 =

1 per 1000

P < 0.001

Cigarette smoking

Lung canc

er

No lung canc

er

Total

Yes 70a

6930b

7000a+b

No 3c

2997d

3000c+d

Relative risk Relative risThe ratio of

incidence among exposed and incidence among non-exposed

Also called ‘risk ratio’

RR=

RR is the direct measure of strength of association between suspected cause and effect

Incidence among exposedIncidence among non-exposed

=

10/1 = 10

Cigarette smoking

Lung canc

er

No lung canc

er

Total

Yes 70a

6930b

7000a+b

No 3c

2997d

3000c+d

RR-i= no assossiationRR > 1= positive assossiation

Attributable risk

The difference in incidence rates between exposed and non-exposed groups

Also called risk difference

of

lung cancer was due to their smoking It indicates to what extent disease can be

attributed to the exposure Suggests the amount of disease that might be

eliminated if the factor could be controlled

Incident rate among exposed – incidence rate among non-exposedIncident rate among exposed

X 100

(10-1/10) X 100 = 90%

Relative risk X Attributable risk

Relative risk Etiological enquiries Larger the RR,

stronger the association between risk factor and outcome

Does not reflect the potential public health importance

Attributable risk Gives a better idea of

the impact of a successful intervention might have in reducing the problem

Advantages of cohort studies

Allow the possibility of measuring directly

the relative risk of developing the condition for those

who have the characteristic, compared to those who

do not

Allows for a conclusion of cause-effect relationship

Because the presence or absence of the risk factor is

recorded before the disease occurs, there is no chance

of bias

Cohort studies are capable of identifying

other diseases that may be related to the

same risk factor. Unlike case-control studies, cohort studies

provide the

possibility of estimating attributable risks,

thus indicating the absolute magnitude of

disease attributable to the risk factor.

Disadvantages of cohort studies Not always feasible. Relatively inefficient for studying rare conditions. They are very costly in time, personnel, space and patient

follow-up. Sample sizes required for cohort studies are extremely large,

especially for infrequent conditions; it is usually difficult to find

and manage samples of this size. The most serious problem is that of attrition, which can affect the

validity of the conclusion, if it renders the samples less

representative, or if the people who become unavailable are

different from those actually followed up. The higher the

proportion lost (say beyond 10-15%) the more serious the

potential bias.

There may also be attrition among investigators who maylose interest, leave for another job, or become involvedin another project.

Over a long period, many changes may occur in theenvironment, among individuals or in the type ofintervention, and these may confuse the issue ofassociation and attributable risk.

Case control study cohort study

Proceeds from effect to cause Starts with the disease Tests whether the suspected

exposure occurs more frequentlyin those with the disease thanamong those without thedisease.

Involves fewer number ofsubjects

Yields relatively quick results Suitable for the study of rare

diseases Generally yields only estimate

of RR (odds ratio) Cannot yield information about

diseases other than thatselected for study

Relatively inexpensive

Proceeds from "cause to effect". Starts with people exposed to risk

factor or suspected cause. Tests whether disease occurs more

frequently in those exposed, than in those not similarly exposed.

Involves larger number of subjects

Long follow-up period often needed, involving delayed results.

Inappropriate when the disease or exposure under investigation is rare.

Yields incidence rates, RR as well as AR.

Can yield information about more than one disease outcome.

Expensive.

Experimental studies

Study of epidemics among colonies of experimental animals such as rats and mice .

AIMS To provide scientific proofs of etiological factors To provide a method of measuring the effectiveness and

efficiency of health services has all adv and disadv of cohort study and also

ethics,cost and feasibility Animal studies: important applicationAdvantages1. Bred in lab,and can manipulated easily2. They multiply rapidly Disadvantages:3. Not all human diseases can be reprodeuced4. All conclusions – not applicable

Human studies:To investigate disease etiology and to evaluate the

preventive ,therapeutic measures1747-john lind-scurvy1796-Edward Jennar-cowpox 1. Ethical and logistic considerations,benefits

weighed againsts the risks involved2. Volunteers –made fully aware of the experiment3. WHO (1980)-strict code of practice

Experimental studies

Randomised controlled trials:

Involves some action,intervention or manipulation such as deliberate application or withdrawl of suspected cause.

1. Drawing up a protocal

2. Selecting reference and experimental population

3. Randomization

4. Blinding

5. Manipulation or intervention

6. Follow- up

7. Assessment of outcome

Randomised controlled trials

Non-randomized trials

Select population (Reference or target population)

Select suitable sample (Experimental or study population)

Selection by defined criteria

Potential participants (Meet selection criteria)

Non-participants(do not meet selection criteria)

Invitation to participate Non-participants(do not give consent)

Participants

Randomization & double blinding

Experimental group Manipulation,Follow up

& Assessment

Control group

DEsiGN oF

aN

RCT-DB

Positive results: benefit of exp measure----reduced incidence or severity of disease or other appropriate outcomes of study.

Negative results: severity and frequency of side effects and complications ,if any death

Blinding: Randomization cannot guard against these sorts of bias nor the

size of the sample.the technique known as blinding is adopted which can be done in

Single blind trial: here the participant is not aware whether he belongs to study

group or control group. Double blind trial; Here neither the doctor nor the participant is aware of the group

allocation and the treatment received.Triple blind trial: Here the participant,the investigator and the analyzer are all

‘’blind’’.

Ethics in research

First important code of ethics was the NURENBURG CODE of 1947. “No research could proceed in human subjects without voluntary consent.”

Declaration of Helsinki code of ethics on principles of ethical behaviour was established in HELSINKI-I in 1975.

The term “clinical research” to “biomedical research” was revised in HELSINKI- II in 1975

institutional ethics committee or institutional review board

Institutions undertaking clinical trials have to constitute an Institutional Ethics Committee (IEC) or Institutional Review Board (IRB).

It is mandatory that each dissertation research proposal (synopsis) involving humans (irrespective of type of study, including questionnaire based surveys) or animals should be accompanied by a clearance letter from IEC.

ethics and its principles

The science of ideal human character and behavior in situations where distinction must be made between right and wrong, duty must be followed and good inter-personal relations maintained.

When considering the ethical aspect of health research the following principles should also be kept in mind. (Helsinki declaration)

Ethical principles

1. Non-malificence2. Benificience 3. Veracity or truthfulness4. Autonomy5. Justice6. Confidentiality

An application should be submitted to the ethics committee in the following manner 1. Clear research objectives and rationale for

undertaking the investigation in human subjects in the light of existing knowledge.

2. Subject recruitment procedures.

3. Inclusion and exclusion criteria for entry of subjects in the study.

4. Precise description of methodology of the proposed research, including intended dosage of drugs, planned duration of treatment and details of invasive procedures if any.

5. A description of plans to withdraw or withhold standard therapies in the course of research.

6. The plans for statistical analysis of the study.

7. Procedure for seeking and obtaining informed consent with sample of patient information sheet and informed consent forms in English and regional languages.

8. Safety of proposed intervention and any drug or vaccine to be tested, including results of relevant laboratory and animal research.

9. For research carrying more than minimal risk, an account of plans to provide medical therapy for such risk or injury or toxicity due to over dosage should be included.

10. Proposed compensation and reimbursement of incidental expenses.

11. Storage and maintenance of all data collected during the trial.

12. Plans for publication of results- positive or negative- while maintaining the privacy and confidentiality of the study participants.

13. A statement on probable ethical issues and steps taken to tackle the same.

Considerations to be kept in mind while conducting research:

In any research on human beings, each subject must be adequately informed of the aim, methods, anticipated benefits and potential hazards of the study and the discomfort it may entail.

When obtaining informed consent, we should be cautious if the subject has a dependent relationship to us. No pressure or threat should be exercised.

In case of legal incompetence informed consent should be obtained from the legal guardian in accordance with the existing legislation.

Subject should be informed that they are free to abstain or to withdraw from participation at any time

references Behavioural sciences for dentistry. G.Humphris &

M.S.Ling. Churchill Livingstone.2000.

Health research methodology- a guide for training in research methods. WHO 1992

Critical thinking; understanding and evaluating dental research. D.M.Brunette. Quintessence publishing. 1996.

Dentistry, dental practice and community. 5th edition. B.A. Burt & S.A.Eklund. WB Saunders company.

Park’s text book of preventive and social medicine. 19th edition. K.Park. Bhanot publishers. 2007.

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