Home 
Contact 
Profile 
Videos 
Lecture at a program “Research Methodology in Health Sciences Course” held at Northern Area Armed Forces Hospital, Hafr Al Batin on 28 December 2020 at 4.20pm. By Professor Omar Hasan Kasule MB ChB (MUK), MPH (Harvard), DrPH (Harvard) Chairman, Institutional Review Board - KFMC
SOURCES OF SECONDARY DATA:
} Secondary data is from
decennial censuses, vital statistics, routinely collected data, epidemiological
studies, and special health surveys. Census data is reliable. It is wide in
scope covering demographic, social, economic, and health information. Vital
events are births, deaths, Marriage & divorce, and some disease conditions.
} Routinely collected data are cheap but may be
unavailable or incomplete. They are obtained from medical facilities, life and
health insurance companies, institutions (like prisons, the army, and schools),
disease registries, and administrative records.
} Observational epidemiological studies are of
3 types: cross-sectional, case-control, and follow-up/cohort studies.
} Special surveys cover a larger population
than epidemiological studies and may be health, nutritional, or
socio-demographic surveys.
PRIMARY DATA COLLECTION BY QUESTIONNAIRE:
} Questionnaire design involves content,
wording of questions, format and layout.
} The reliability and validity of the
questionnaire as well as practical logistics should be tested during the pilot
study.
} Informed consent and confidentiality must be
respected.
} A protocol sets out data collection
procedures.
} Questionnaire administration by face-to-face
interview is the best but is expensive. Questionnaire administration by
telephone is cheaper.
} Questionnaire administration by mail is very
cheap but has a lower response rate.
} Computer-administered questionnaire is
associated with more honest responses.
QUESTIONNAIRE DESIGN: CONTENT:
} Correct decisions must be made about what
items to include in the questionnaire guided by the hypothesis under study and
knowledge of potential confounding factors.
} A start is made by reviewing questionnaire of
previous similar studies.
} The content of a question may be one of the
following: knowledge, attitude, belief, experience, behavior, and attributes.
QUESTIONNAIRE DESIGN: WORDING OF QUESTIONS:
} Main objectives in selecting questionnaire
items: clarity, comprehensibility, neutrality and scaling.
} The question must be worded properly to make
sure they are easy to understand.
} The wording of the questionnaire items should
leave no room for ambiguity.
} The words must be easy. Technical jargon must
be avoided.
} The wording should be neutral, neither
positive nor negative.
} Biased questions are leading, threatening,
value-laden, or assumptions.
} Each question should contain only one concept
or item of information; questions should not be double barreled.
} The responses must be scaled appropriately.
} Double negatives should be avoided.
FORMAT AND LAYOUT:
} The order of the questions must be logical
moving from the superficial to the more detailed.
} Skip patterns should be worked out carefully
and exhaustively.
} Embarrassing questions should be kept towards
the end because they may spoil the whole interview.
} Closed questions are preferred to open
questions.
} Questions should not be too long.
} The total number of questions must be
appropriate
} The questionnaire should be designed for easy
reading. Use of boxes and different colors helps.
} The font print size must be readable.
ETHICAL AND CONFIDENTIALITY ISSUES:
} Informed consent must be obtained.
} The information provided could be subpoenaed
by a court of law and the investigator cannot refuse to release it.
} In the course of the interview the
investigator may get information that requires taking life-saving measures. Taking
these measures will however compromise the confidentiality. Such a situation
may arise in case of an interviewee who informs the interviewer that he is planning
to commit suicide later that day. Such information may have to be conveyed
immediately to the authorities concerned.
PREPARATION FOR DATA COLLECTION - 1:
} Data collection processes must be clearly
defined in a written protocol which is the operational document of the study.
} The protocol should include the initial
version of the questionnaire. This can be updated and improved after the pilot
study.
} If a paper questionnaire is used data
transfer into the electronic form will be necessary. The need for this could be
obviated by direct on-line entry of data.
} The objectives of the data collection must be
defined clearly. Operational decisions and planning depend on the definition of
objectives. It is wrong to collect more data than what is necessary to satisfy
the objectives.
} It is also wrong to collect data just in case
it may turn out to be useful.
} The study population is identified. The
method of sampling and the size of the
sample are determined.
PREPARATION FOR DATA COLLECTION - 2:
} Staff to be used must be trained. The
training should go beyond telling them what they will do. They must have
sufficient understanding of the study that they can detect serious mistakes and
deviations.
} A pilot study to test methods and procedures
should be carried out. However well a study is planned, things could go wrong
once field work starts. A pilot study helps detect and correct such pitfalls.
} A quality control program must be part of the
protocol from the beginning.
} Proxy or surrogate respondents must be used
when the subject in handicapped or is not available. The next of kin is usually
selected for this. Sometimes the subject and the proxy may disagree. In some
case control studies, dead controls are selected for dead cases and proxies are
interviewed for both series.
} Response can be increased by obtaining
sponsorship by the government or some other
official body that credibility to the study.
} Participation is also maximized by short
follow up periods, regular feedback, and causing the participants as little
inconvenience as possible.
QUESTIONNAIRE ADMINISTRATION BY FACE-TO-FACE INTERVIEW:
} In a face-to-face interview, the interviewer
reads out questions to the interviewee and completes the questionnaire. The
interview may be structured or unstructured.
} The interviewer should make sure that
circumstances of the interview are optimal in terms of place and time.
} The interviewers should be selected carefully
and adequately trained. They should be given an interviewer’s manual to guide
them. It is important that interviewers are continuously monitored.
ADVANTAGES OF FACE-TO-FACE QUESTIONNAIRE ADMINISTRATION:
} The interviewer can establish the identity of
the respondent. In mailed questionnaire the answers may be from another person
other than the intended respondent.
} There are fewer item non-responses because of
the presence of the interviewer who will encourage and may coax the respondent
to answer all items.
} The interviewer can clarify items that the
respondent does not understand or is likely to misunderstand.
} There is flexibility in the sequence of the
items.
} Open-ended questions are possible.
} Items irrelevant to the particular
interviewee can be dropped thus saving time.
DISADVANTAGES OF FACE-TO-FACE QUESTIONNAIRE ADMINISTRATION:
} It costs more in terms of time and money. The
interviewer has to travel, search for, and spend time with the respondent.
} A prior appointment is needed to ensure that
the respondent will be available at the place and time of the proposed
interview.
} Personal chemistry may not work well. The
interviewee may resent the interviewer on the basis of gender, ethnicity, or
any other personal and behavioral characteristic.
} The presence of the interviewer may influence
interviewee responses in a subtle way. The interviewee may try to give
responses that he thinks are acceptable to the interviewer on the basis of the
interviewer's gender, race, SES, and suggestive questioning.
} The common errors in face to face interview
are omitting a question, too much or too little probing, failure to record
information, and cheating by the interviewer.
ADVANTAGES OF QUESTIONNAIRE ADMINISTRATION BY TELEPHONE:
} Considerable savings in time and money. It is
possible to conduct a nationwide survey sitting in one office.
} Has fewer item non-responses because of the
personal contact involved.
} Skip patterns can be followed to save time.
} Difficult questions can be explained.
} Interviewer bias is less than in face-to-face
interviews.
} Telephone interviews must also be supervised
for optimal results. The supervisor should listen in as the interview is
conducted.
DISADVANTAGES OF QUESTIONNAIRE ADMINISTRATION BY TELEPHONE:
} Selection bias may operate when the study
sample includes only those who have telephones and the telephone numbers are
listed. The problem of unlisted numbers can be overcome by use of random digit
dialing.
} Selection bias may arise due to the day and
time of day that the telephone call is
placed. Office workers will be missed in early morning calls. Workers on night
shifts will be missed in evening calls.
} It is not possible to be sure whether the
person at the other end of the line is the actual intended respondent.
IMPROVEMENT OF TELEPHONE INTERVIEWS BY USE OF COMPUTERS:
} Computer-assisted telephone interview can
make the process quicker when the interviewer is prompted by the computer.
} The computer will work out the skip patterns
and will alert the interviewer to responses that are inappropriate or
contradictory.
QUESTIONNAIRE ADMINISTRATION BY MAIL - 1:
} In the method of questionnaire administration
by mail, a questionnaire is mailed to the respondent's address. The respondent
completes and returns the questionnaire in a pre-addressed and stamped
envelope.
} Questionnaire administration by mail has 2
main advantages: (a) it is the cheapest method of data collection (b) There is
no bias due to interviewer involvement.
} The disadvantages of mail questionnaires are:
(a) low overall response (b) Higher item non-response (c) Delays in returning
the questionnaire.
QUESTIONNAIRE ADMINISTRATION BY MAIL - 2: Measures To Improve Response
} Sending the questionnaire with a personalized
cover letter.
} Promising a token of appreciation for return
of the questionnaire.
} Making the questionnaire anonymous by not
including any information on the returned questionnaire that can be used to
identify a particular individual.
} Provide a self-addressed and stamped
envelope for the response using pre-coded questionnaires so that all the
respondent has to do is to select
responses.
} Follow up by letter for those who delay in
returning the questionnaires.
COMPUTER-ADMINISTERED QUESTIONNAIRE: Advantages
} It frees the interviewer's time.
} There are no transcription errors because
information in entered on-line.
} No items are missed because the computer will
not allow the respondent to move to the next item before answering the previous
one.
} The respondent can give more honest responses
when facing an anonymous computer than when faced by a human interviewer.
COMPUTER-ADMINISTERED QUESTIONNAIRE: Disadvantages
} The disadvantage of computer-administered
questionnaires is that the respondent does not have the opportunity to vary the
order of questions to his convenience.
PHYSICAL PRIMARY DATA COLLECTION:
} Data can be obtained by clinical examination,
standardized psychological/psychiatric evaluation, measurement of environmental
or occupational exposure, and assay of biological specimens and laboratory
experiments.
} Pharmacological experiments involve bioassay,
quantal dose-effect curves, dose-response curves, and studies of drug elimination.
} Physiology experiments involve measurements
of parameters of the various body systems.
} Microbiology experiments involve bacterial
counts, immunoassays, and serological assays.
} Biochemical experiments involve measurements
of concentrations of various substances.
} Statistical and graphical techniques are used
to display and summarize this data.
DATA MANAGEMENT - 1:
} Self-coding or pre-coded questionnaires are
preferable.
} Data is input as text, multiple choice,
numeric, date and time, and yes/no responses.
} In double entry techniques, 2 data entry
clerks enter the same data and a check is made by computer on items on which
they differ.
} Data in the computer can be checked manually
against the original questionnaire.
} Interactive data entry enables detection and
correction of logical and entry errors immediately.
} Data replication is a copy management service
that involves copying the data and also managing the copies. Synchronous data
replication is instantaneous updating with no latency in data consistency. In asynchronous
data replication the updating is not immediate and consistency is loose.
DATA MANAGEMENT - 2:
} Data editing is the process of correcting
data collection and data entry errors.
} The data is 'cleaned' using logical,
statistical, range, and consistency checks.
} All values are at the same level of precision
(number of decimal places) to make computations consistent and decrease rounding
off errors.
} The kappa statistic is used to measure
inter-rater agreement.
} Data editing identifies and corrects errors
such as invalid or inconsistent values.
} Data is validated and its consistency is
tested.
DATA MANAGEMENT 3: Main Data Problems
} Missing data,
} Coding and entry errors,
} Inconsistencies,
} Irregular patterns,
} Digit preference,
} Out-liers,
} Rounding-off / significant figures,
} Questions with multiple valid responses,
} Record duplication.
DATA MANAGEMENT: Data Transformation
} Data transformation is the process of
creating new derived variables preliminary to analysis.
} Mathematical operations such as division,
multiplication, addition, or subtraction; mathematical transformations such as
logarithmic, trigonometric, power, and z-transformations.
DATA ANALYSIS:
} Data analysis consists of data summarization,
estimation and interpretation.
} Simple manual inspection of the data is
needed before statistical procedures.
} Preliminary examination consists of looking
at tables and graphics.
} Descriptive statistics are used to detect
errors, ascertain the normality of the data, and know the size of cells.
} Missing values may be imputed or incomplete
observations may be eliminated.
DATA ANALYSIS: Statistical Tests
} Tests for association, effect, or trend
involve construction and testing of hypotheses.
} The tests for association are the t,
chi-square, linear correlation, and logistic regression tests or coefficients.
} The common effect measures are: Odds Ratio,
Risk Ratio, Rate difference.
} Measures of trend can discover relationships
that are not picked up by association and effect measures.
} The probability, likelihood, and regression
models are used in analysis.
} Analytic procedures and computer programs vary
for continuous and discrete data, for person-time and count data, for simple
and stratified analysis, for univariate, bivariate and multivariate analysis,
and for polytomous outcome variables.
} Procedures are different for large samples
and small samples.