Quanti - Research Design Flashcards
2What is a research design?
The researcher’s overall plan for
- Answering the research questions
- Testing the research hypothesis
- Used to show how all of the major parts of the research project – the samples, measures, treatments or intervention – work together to try to address the research questions
Key Research Design Features
- Intervention
- will there be an intervention - Comparison
- what types of comparisons will be made? - Control over confounding variables
- how will confounding variables be controlled? - Time frames
- how often will data be collected? - Relative timing
- when will information on IV and DV be collected?
- looking backward or forward? - Location
- where will the study take place?
Types of quantitative research designs
- Control over independent variable?
* Experimental
* Quasi-experimental
* Non-experimental - Data Collection - How often
* Cross-sectional
* Longitudinal - Data Collection - when
* Retrospective
* Prospective
What is the difference between a cross-sectional and longitudinal research design?
- Cross-sectional design:
- Data are collected at one point in time
- Longitudinal design:
- Data are collected at two or more points over an extended period
Is this a longitudinal or cross-sectional design?
Assess patients’ QoL at 1 week after their heart attack (using WHOQoL scale)
Cross-sectional
Is this a longitudinal or cross-sectional design?
Assess patients’ QoL at 1 week after their heart attack and again at 3 months and at 12 months after their heart attack (using WHOQoL scale)
Longitudinal
What are the strengths and weaknesses of cross-sectional designs?
- Are appropriate for describing phenomena at a fixed point;
- Are economical and easy to manage;
- But pose problems for inferring changes over time!
What are the strengths and weaknesses of longitudinal designs?
- Are useful for studying changes over time and for establishing sequencing of a phenomena;
- Loss of participants (attrition) over time; !
- Risk of faulty inferences.!
What is a retrospective research design?
Examine what has happened in the past.
- Data begins with outcome (DV) and looks backward for
cause or influence(IV).
What is a prospective research design?
- Investigate the outcome (DV) in the future.
- Data begins with IV and looks forward for the effect.
Is this a retrospective or prospective research design?
Examine the causes of emergency admission in a public hospital in Singapore
Retrospective
Is this a retrospective or prospective research design?
Examine the effects of a counseling service on the extent of marital problems.
Prospective
Strengths and weaknesses of a retrospective research design
- Relatively inexpensive
- Smaller numbers required
- Quicker to complete
- Prone to recall/retrospective bias!
Strengths and weaknesses of a prospective research design
- Yields true incidence rates and relative risks
- Expensive
- Requires large numbers
- Takes a long time to
complete - Prone to attrition bias!
What types of research designs involves control over the independent variable?
True experimental (RCT)
Quasi-experimental
Non-experimental
What is a Randomised Controlled Trial (RCT)?
Most powerful approach to test a cause-and- effect
relationship between Intervention (IV) and Outcome
(DV)
What is a pretest-posttest design?
- Random assignment of subjects to experimental and control group
- Outcomes (DV) measured before the intervention
- Intervention (IV) administered to experimental group
- Outcomes (DV) measured after intervention
What are the characteristics of a true experiment?!
- Intervention
- Manipulation of independent variable - Control
- Recruitment of a control group - Randomisation
– Assignment of participants to a control or experimental condition on a random basis
What is randomisation in a true experimental research?
- process by which allocation of subjects to control or
experimental groups is done BY CHANCE - Every subject has an EQUAL CHANCE of being included in
either group - Randomly assigned groups are to be comparable with
respect to an infinite number of biological, psychological
and social traits (intrinsic factors, e.g., age) at outset of the study - Group differences on outcomes (DV) observed can
therefore be inferred as being caused by the intervention
(IV)
What are some methods of randomisation?
- Flipping a coin
- Pulling names from an envelope
- Table of random numbers
- Researcher randomizer
https://www.randomizer.org/
What are the strengths of a true experimental design (RCT)?
- Most powerful design for testing hypotheses of cause-and-effect relationships.
- “gold standard” for intervention studies
– manipulation: IV is consciously manipulated by offering to one group
– randomization: ensure the study groups are equivalent and comparable in terms of intrinsic factors (e.g., age)
– control: provide a basis for comparison as both groups are expose to same external factors
- The difference in DV between two groups is due
to IV
What are the key characteristics of a Quasi-experimental research?
- Intervention: Manipulation of IV
- ABSENCE OF RANDOMISATION OF SUBJECTS
- Control (may/may not have): Recruitment of a control group
What are the strengths of a Quasi-Experimental Research?
Practical
- It is difficult or impossible to deliver an innovative treatment randomly to some people but not to others
- People are not always willing to be randomized in clinical
trials
What are the weaknesses of a Quasi-Experimental Research?
- Weaken the cause-and-effect relationship
- Absence of randomization
implied change in DV = effect of IV + initial group difference in internal factor
- Absence of a control group
implied change in DV = effect of IV + effect of unknown
external factor
