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Data Collection Bakr M. Bin Sadiq Pediatric Specialist
Senior Clinical and Field Epidemiologist Certified in International Research Ethics
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Objectives Kinds of data collection tools and techniques
The benefits of using a combination of different data collection techniques Sources of bias in data collection, and ways to prevent bias
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Where to start! Before designing a method of data collection, the researcher should write: Detailed information on the subject of data to be collected. Concepts to be measured in the study
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Selecting Study Variables
Define the keywords contained in the research questions Operationalize these keywords Concept Indicator Income Monthly net salary GP workload Number of patients seen Referral rate Patients sent to outpatients Elderly Aged over 65
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Data Collection Techniques vs. Data Collection Tools
Record Sources Checklist, formats Observing Eyes, pen/paper, watch, scale, microscope, checklist Interviewing Interview schedule, checklist, tape recorder Focus group discussion FGD guide, tape recorder Written questionnaire Questionnaire
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Data Collection Techniques
Recorded Sources Observation Interview Focus group discussion Written questionnaire
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Recorded Sources A data collection technique that involves locating and analyzing information that has already been collected (old data) Advantage Not expensive Permits examination of trends over the past Disadvantage Difficulty in gaining access (privacy) Information recorded may be biased
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Observation Observation is a technique which involves systematically selecting, watching and recording behavior and characteristics of living beings, objects or phenomena.
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Observation Advantage Disadvantage Give more detailed information
Allow to collect information on facts not mentioned in the questionnaire Allow to test reliability of responses to questionnaire Disadvantage Observation bias Presence of researcher can influence the situation
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Interview An interview is a data collection technique that involves oral questioning of respondents, either individually or as a group
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Interview Advantage Disadvantage Suitable for illiterates
Clarification of questions is possible Higher response rate Disadvantage Presence of researcher can influence responses Records of events may be less complete than with observations
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Focused group discussion
A focused group discussion consists of a group discussion in which a small number of participants (usually 6 to 12 ) of similar status under the guidance of a moderator and with at least one additional observer talk about topics of relevance to particular study.
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Focused group discussion
Advantage Provides in-depth qualitative information Disadvantage Shy participants Domineering participants
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Written questionnaire
A written questionnaire (self-administered) is a data collection technique in which written questions are presented that are to be answered in written form by the respondents themselves.
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Written questionnaire
Advantage No need of research assistant to administer it No bias in asking the questions differently More honest responses Disadvantage Not possible to use illiterate respondents Low rate of response Questions may be misunderstood
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Importance of Techniques Combination
They complement each other Maximizes the quality Reduces the chances for bias
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Bias in Information Collected
A bias is distortion in the data collected such that the information is no longer representative of the true situation
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Sources of Bias Defective instruments, such as:
pre-coded questionnaire – not enough is known about the topic semi-structured questionnaire – no guidelines on how to ask or answer weighing scales – not standardized
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Sources of Bias Observer bias
researcher will only see or hear things in which he is interested it’s preferable to have two persons information has to be recorded and discussed immediately
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Sources of Bias Effects of interviewer on informant
informant may mistrust the intention of the researcher – give misleading answers
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Written Questionnaire Design
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Construction of a questionnaire
A title should be short and clear. An address. An identifier Instructions: tell about the study and how to complete the questionnaire. The layout: the questionnaire should appear neat, and attractive
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Construction of a questionnaire
The ending: it is useful to offer a very open question right at the end. Example: Do you have any further points to make about this questionnaire? Thank you for helping with this study. Testing for problems.
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Wording The objective should be construct questions that are: Simple.
Free of ambiguity. Encourage accurate and honest responses without embarrassing or offending the respondent.
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Clarity Questions must be clear and specific as possible. Example:
How much exercise do you usually get? During a typical week, how many hours do you spend exercising?
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Simplicity Questions should use simple, common words that convey the idea and avoid technical terms. Example: “Drugs you can buy without a doctor’s prescription” “Over-the-counter medications”.
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Neutrality Avoid words that suggest that there is a most desirable answer. Example: During the last month, how often did you smoke too much cigarettes? During the last month, how often did you smoke more than five cigarettes in one day?
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Types of questions There are two basic types of questions:
Open-ended questions. Closed-ended questions.
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Open-ended questions Open ended questions are particularly useful when it is important to hear what respondents have to say in their own words. Example: What habits do you believe increase a person’s chance of having a heart attack? ________________________________________________________________________________________________________
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Open-ended questions Advantages Useful for exploring new areas.
Respondents can say their own words. Disadvantages Require qualitative methods to code and analyze the responses, which take time and subjective judgment.
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Closed-ended questions
Closed-ended questions are more common, these questions ask respondents to choose from one or more possible answers. Example: Which one of the following do you think increase a person’s chance of having a heart attack the most?(check one.) Smoking Being overweight Stress
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Closed-ended questions
Advantages: Quicker and easer to answer. Answers are easier to be analyze. Possible answers often help clarify the meaning of the question. Disadvantages: Lead respondents in certain directions. The possible answers may not include an answer that is most appropriate.
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A structured (standardized) questionnaire
A structured (standardized)questionnaire must be carefully set out and worded. Example: -Total family income per month in Saudi Riyals_____ -What is your height in meter?_____
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A structured (standardized) questionnaire
A self-administered questionnaire -Useful for straight forward information. -For large sample, cheap and quickly. An interview-administered questionnaire -Useful for complicated information. -Produces a higher response rate. -Better quality of information. -More time consuming and expensive.
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Interviewing Methods Personal interviews Telephone surveys
Mail Surveys Computer Direct Interviews Surveys Internet/Intranet (Web Page) Surveys
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Summary Objective Speed Cost
Your choice of data collection methods will depend on several factors: Objective Speed Cost
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