Research

Methodology in

otology BALASUBRAMANIAN THIAGARAJAN

What is ideal research?

Should be reproducible

Should withstand statistical analysis

Should test a theory / hypothesis / belief

Should be beneficial to the public

Should be systematic / empirical / critical /

Should have academic integrity

Should be publishable

Desist finding questions to your answers

Confidence interval

Sample

Confidence interval

Population

Factors affecting confidence

interval

Sample size – Larger the sample size better is the confidence interval

Percentage – Represents the accuracy of the study

Population size – This is least important provided the samples are

randomly selected. This is important when the group is relatively

small and contains known group of people

Confidence level

This tells the researcher how confident the actual mean falls within the

Confident interval. Standard deviation if applied tells the researcher

How much variation that can be expected with the studied sample

Size. Ideal SD value is 0.5.

Sample size calculation

Confidence level = Z This is a constant value

90% - confidence interval - Z score = 1.645

95% - confidence interval - Z score = 1.96

99% - confidence interval - Z score = 2.326

Sample size = (Z-score)2 * Std Dev* (1- SD) / (margin of error)2

((1.96)² x .5(.5)) / (.05)²

(3.8416 x .25) / .0025

.9604 / .0025

384.16

Research styles

objective

subjective

Ethical committee approval is a must for all types of research

Objective type

Physical characteristics

Testing universally applicable rules / laws

Testing hypothesis

Experiments

Surveys

Avoid the lure of numbers. Observation of researcher is more vital

Subjective type

Involves social life of groups

This study is usually conducted by observation and the findings

documented and explanations attempted for the observations

Usually social scientists use this modality

Always assume that your work will be scrutinised by the public

Types of objective study design

Descriptive

Analytical

Interventional

Greatest danger is not failure but non submission of your work

Descriptive study design

These studies consider variance of disease in respect of time, place

and person. Classic example of this design would be an attempted

study on the incidence of age related degree of progressive sensori neural hearing loss.

These studies provide clues that can be used to design elaborate

analytical studies.

Two types of descriptive studies are possible i.e. cross sectional and

longitudinal.

Cross sectional study (Descriptive Design)

This study is based on single examination of cross section of

population performed at one point of time

Results can be projected on the whole population provided the study is random in nature

This is a fast and inexpensive way of ascertaining incidence of a

disease

Cross sectional study - Steps

Objective of the study should be clearly defined

Population under study should also be defined clearly

Disease / health problem to be studied should also be defined

clearly (diagnostic criteria should be laid down)

Randomization of the sample should be ensured

Double blind trial has more validity

Make a list of variables

Prepare a questionnaire

Decide on a sample size

Longitudinal study (Descriptive design)

Observations are repeated in the same population over a

prolonged period of time by means of follow up examinations

Natural history of disease and its future outcome can be studied

Helps in identification of risk factors in disease causation

Also helps in finding out the incidence rate

Advantages of descriptive studies

Provides morbidity and mortality data

Provides clue to disease etiology

Generates hypothesis which can be tested by analytical studies

Provides data for planning, organizing and evaluating preventive

and curative services

Contributes to research in terms of disease occurrence by time

place or person

Analytical study design

Classic example of this design would be the study to ascertain odds

of developing noise induced hearing loss.

Intensity / duration of noise exposure should be factorized.

Age and sex of the patient (variables).

Analytical study design could be prospective and retrospective

Prospective study design (cohort /

longitudinal)

Difficult to perform

Tests the hypothesis obtained by descriptive study

Should proceed from cause to effect

This study is carried out on healthy people on whom exposure has

occurred and disease has not

Vulnerable groups should be followed over a period of time to

identify the risk factor

Costly to perform

Cohort study design

Population

People without disease

Exposed Un Exposed

Disease No Disease Disease No Disease

Retrospective study (case control

study)

Easy to design and perform

This study is performed based on medical records

Study includes cases with health problems and controls without

disease

They should be matched evenly age for age and sex for sex to be

valid

Randomisation is a must

Cost of study affordable

Interventional study

Interventional studies attempt to demonstrate the cause-effect

relationships by altering the natural history of the disease by

intervention aimed at reducing the exposure to the offending agent. (Sound in this case)

Control group should be included for comparison

Randomization should be followed to remove bias

Single / double blind protocol can be followed

Beware of variables

They should be identified correctly

Incorrect identification of variables will invalidate the entire research

Factors that could invalidate the entire research should be listed

and factorised

The trick is in trying to unearth surprising variables

List some of the variables in our

hypothetical project

Intensity of noise in decibel

Number of hours of exposure / day

Exposure of workers to ototoxic drugs

Surprising variable – temporary / permanent threshold shift

Common pitfalls

Sample size

Variables

Improperly formulated questionnaire

Improperly matched control

Types of sample

Convenient sample (ideally suited for our research scenario taken

up here)

Judgement sample (according to the one who is familiar with the characteristics of the population under study)

Random sample (gives the most accurate and validated result)

Sample size

Don’t hesitate to take the help of statistician at this stage

For any successful research the confidence level should at least be

above 90% with error value of a minimum 5-10%

Avoid online sample calculators

Variables – dependent /

independent variables

All experiments contain variables at least one if not more

These can be measured / studied

Dependent variable – is dependent on independent variable

Categorical variables

Nominal variables – Can have two / more categories

Ordinal variable – can have two / more categories that can be

ranked

Dichotomous variable – can have only two categories (either or) like

male / female

Continuous variables

These are quantitative

Classified into interval or ratio variables

data analysis

Attempt must be made to summarize the observed variables

If many variables are taken into consideration then coding and

categorization should be performed

Study of frequency distribution should be resorted to analyse

complex data

Data should be displayed as bar diagram / pie chart / histogram /

frequency distribution curves / x-y plots

Line graphs

Useful in tracking changes over a

period of time

Smaller changes are better

displayed

Can also be used to compare

changes over time even for more

than one group by changing the

colour of the line

Bar graphs

Can be used to compare things

between different groups

Can also be used to track

changes over course of time

This graph suits best if the changes

are larger

Pie charts

Best used when comparing parts

of a whole

Cannot be used to show changes

over a period of time

Area graphs

Similar to line graphs

Can be used to track changes

over time

Groups must be categorized

before displaying

X-y plot

Used to determine relationships

between two different things

X-axis is used to plot one variable

and the y-axis is used to plot the

other

If both variables increase at the

same time it is positive relationship

If one variable increases while the

other decreases it is negative

relationship

Mean / median / mode

Mean – is nothing but an average. It is the sum of values divided by

the number of values

Median is the value that divides the distribution into half

Mode is the value that occurs most often

Variance / standard deviation

This is the most preferred method of variation

It uses all the observation

Variations would be small if the observations are bunched closely

Variations if averaged will always be zero because positive

deviations away from the mean would cancel out the negative

deviations away from the mean

Squaring the average of deviations is resorted to, and this average

of squared value would always stay positive

Standard deviation is a measure of how spread out the numbers are. It is actually the square root of variance and is indicated by

Greek letter sigma

explanation

Measured heights of dogs in mm

Mean = sum of all the heights

divided by 5 (394 mm)

Explantion (contd)

calculation

Variance can be calculated by squaring the differences and

averaging them (21704)

Standard deviation is square root of variance = 147. This number helps in comparison.

Use p values / chi-square test to test hypothesis

Before choosing a topic

Conduct feasibility study

Is it possible to complete within the given time frame

Affordability

Institutional support

Can you obtain necessary literature?

Will the topic be relevant after the completion?

Check list

Exact date of submission

Any word limitations

Intermediate deadlines to meet

Rules regarding the publication format

Tutorial support available

Points to be borne in mind

No harm should come to participants in the research (physical /

mental / social)

Children / elderly / mentally retarded should not be exploited

No physical / environmental damage should be caused

Anonymity / privacy should be ensured

Nothing should be done that would bring disrepute to the institution

Interviewer conduct

Friendly and formal

Schedule to be followed

Prior appointment to be sought

Treat all interviewees the same

Prompt don’t direct

Do not volunteer answers

Never be patronising

Be patient

Some useful research topics in

otology

Incidence of conductive deafness in children and their causes

Incidence of noise induced hearing loss

Measles infection – does it cause otosclerosis ?

Acceptability of hearing aids

Age related normal hearing in Indians

Title

Start off with a draft title

Keep polishing it

Avoid question marks in title

Include the period and place of study in the title if possible

aim

Here the aim of the study should be stated

Inclusion and exclusion criteria may be stated here as a

subheading (ideally done in materials and methods)

Introduction - chapter

Should contain an outline of your research

Should contain details of what prompted you to undertake the

study

It should also state concisely what you plan to do and where you

plan your work

Start writing this chapter first, edit it after completing the project

Literature review

This is central to all research

It informs the reader how well you have prepared for the topic

Here you take the opportunity to acknowledge other’s work

It also informs the reader the road you plan to take

Materials and methods

Here the exact research methodology followed is described

There should be a description of the tests used

Inclusion and exclusion criteria should be discussed in detail

result

Data should be presented

Data analysis should be presented here

Statistical tool used for the analysis should be discussed here

conclusion

Take time writing this one

Give your conclusions point by point in clear terms

Results should not be repeated but summarized here

Practical recommendations can be included here

Bibliography

List down all the references and citations

All references and citations should easily be identifiable

appendix

The material given here is for optional reading

Copy of questionnaire

Interview schedule

Copy of ethical committee approval

Copy of institutional approval