Lecture 4 Flashcards
What is the definition of historical research? What are the 2 types of sources and what is the difference between them?
• Seeks to explore events and information from the past in order to provide a better understanding of the present with implications for the future
– Answers the question “what was
• Limited to synthesis and interpretation of data that already
exists
– Primary sources
• Original materials of participants, eyewitnesses, etc.
– Secondary sources
• Materials based on second-hand accounts, individuals not present, etc
What is the difference between the experimental group and the control group?
Experimental designs in human kinetics allow researchers to identify the effects of a specific intervention on a health outcome in a group of people (experimental group) while simultaneously monitoring changes in the same health outcome in people not receiving the intervention (control or comparison group)
What is the purpose of experimental research?
Purpose is to investigate cause-and-effect relationships among variables
– Experimental vs. control groups
– Treatment differs by group
– Always involves manipulation of the IV
What are the 3 criteria for cause and effect?
- The cause must precede the effect in time
- The cause and effect must be correlated with each other
- The correlation between cause and effect cannot be explained by another variable
What is the basic minimum for experimental research? What is the definition of that thing?
Internal validity is considered the basic minimum for experimental research
Did the treatments (IV) cause the change in the outcome (DV)
What are the 2 types of threats to internal validity?
The 2 types of threats are threats associated with participants and threats associated with measurement
What are 4 examples of participant threats to internal validity?
Selection bias
– Sampling bias that results from differential selection of respondents for
the comparison groups.
• *non-random participant selection
• Maturation Effect
– Effect on experimental results caused by experimental subjects maturing
or changing over time (biological or psychological)
• e.g., aging, fatigue, growth
• Mortality or Sample Attrition
– Results from the withdrawal of some subjects from the experiment before
it is completed
– Effects randomization
– Especially troublesome if some withdraw from one treatment group and
not from the others (or at least at different rates)
• History Effect
– events occurring at same time as study not part of the treatment
• e.g., stress, uncontrolled events, illness
What are 3 examples of measurement threats to internal validity?
• Statistical regression
– when groups are selected based on extreme scores
• E.g. “you can only go up from here”
• Textbook example: students playing in a schoolyard
• Testing Effect
– In before-and-after studies, pretesting may sensitize subjects when taking
a test for the 2nd time. (familiarity)
– May cause subjects to act differently than they would have if no pretest
measures were taken
• Instrumentation Effect
– Caused by a change in the wording of questions, in interviewers, or in
other procedures used to measure the dependent variable.
What are 5 ways to defend against threats to internal validity? what is the definition of a stratified random sample?
• Random selection
• Random assignment or Double-blind setups
• Reactive effects of testing
– Eliminate pretest/familiarization session
• Instrumentation
– Calibration and test reliability
– Halo effects (previous knowledge can influence an
observer’s evaluation)
• Limit experimental mortality
The population is divided into two or more groups called strata, according to some criterion, such as geographic location, grade level, age, or income, and subsamples
are randomly selected from each strata.
What are the 2 types of external validity?
• Population Validity
– The extent to which the results can be generalized from the experimental sample to a defined population
• Ecological Validity
– The extent to which the results can be generalized from the set of environmental conditions in the experiment to other environmental conditions
What are 4 threats to external validity?
• Interaction effects of testing – pretest may make participants sensitive to treatment
• Interaction of selection bias & treatment – treatment may work only on participants selected on a specific characteristic
• Reactive effects of experimental setting – setting constraints may influence generalizability
– Hawthorne effect: performance changes when aware of being studied
• Multiple-treatment interference – one treatment may influence the next treatment
What are the 2 ways to defend against threats to external validity?
• Random selection
• Selecting from a larger population
– Participants
– Treatments
– Situations
What are the 3 types of experimental designs?
- Pre-Experimental
- Quasi-Experimental
- True-Experimental
What are 5 key characteristics of pre-experimental designs?
- Weak experimental designs in terms of control
- No random sampling
- No control group
- Threats to internal and external validity are significant problems
- Many definite weaknesses
Why are quasi experiments not true experiments?
• Quasi-experiments resemble true
experiments…
– usually include a manipulation, and provide a comparison.
• …but they are not true experiments.
– lack high degree of control that is characteristic of true experiments.
