Unit 2: Ch. 9 Flashcards
causality
many quantitative research questions are about cause and effect
criteria for making causal inferences? (3)
- the cause must precede the effect
- there must be a demonstrated association between the cause and effect
- the relationship between the presumed cause and the effect cannot be explained by a 3rd variable or confounder (“intervening variable”)
- there can’t be an outside thing influencing the other 2 things
know what’s a cause and what’s an effect
cause comes before the effect (ex: smoking causes lung cancer)
what are the 3 types of quantitative research?
- experiment
- quasi-experiment
- non-experiment (observational studies in medicine)
experiment
offer the strongest evidence on whether a cause (intervention) results in an effect (outcome)
-this is why experiments are high on the evidence hierarchy (strong, but not as strong as systematic reviews)
3 characteristics of a true study?
- intervention
- researcher does something to one group but not the other - control group
- has no intervention but may have a placebo - randomization
- researcher assigns subjects to groups randomly
- “random assignment/selection”
- randomization is the “great equalizer”
quasi-experimental
involves an intervention but lacks one of the other 2 characteristics (either RANDOMIZATION or CONTROL)
non-experimental
a study w/ no intervention
-considered weaker studies than experiments or quasi-experiments; still valuable b/c some variables can’t be manipulated (ex: abuse)
examples of non-experimental studies (9)?
- non-correlational design
- prospective correlational designs
- retrospective studies
- time related study
- cross sectional design: data collected at only one point in time
- longitudinal study: data collected over time - correlation is an association between 2 variables; one may not cause another but one may happen w/ another (correlation ≠ causation)
- prospective design may also be called cohort study by medical researchers (go forward in time)
- retrospective correlational design is when an outcome is present, such as depression
- comparison studies (2 types): one is between subjects (ex: men and women in a study - compare men to women) and a within subjects design (men and women in a study; only compare women w/in the group)
- descriptive: simply describing what’s there
Purpose of control and randomization is to make the groups equal in regards to all factors except the?
intervention
quasi-experiment involves an intervention but?
lacks one of the other 2 characteristics (either randomization or control)
counterfactual
what would happen to people if they were exposed to a causal influence and were simultaneously not exposed to it
most causes are not ____; they only increase the likelihood that an effect will occur
deterministic
John Stuart Mill developed 3 criteria for establishing causal relationships. What are those 3 criteria?
- temporal: a cause must precede an effect in time
- relationship: must be an association between the presumed cause and the effect (ex: an association between smoking and lung cancer)
- confounders: relationship can’t be explained as being caused by a 3rd variable
what are the 3 techniques of research control?
- context: conditions of the study; want the conditions of the study to be held constant (when data is collected, where data is collected, and how data is collected)
- need control over the study context
- communication w/ participants is standardized, using scripts as necessary
- intervention must be delivered according to a plan “treatment fidelity”)
- have to have control over the context (who, what, when, where, and why of your study) - participants: typically done through randomization; also done through homogeneity (want participants to be as much alike on characteristics as possible)
- can be done through matching, statistics and ANCOVA (way of controlling characteristics statistically) - confounders: intervening/extraneous variables; confounding variables not part of the study but can influence findings
- researcher must be aware of what the confounding variables are/might be and control them
- ex: studying stress - there are other things that result from stress that look like the cause
biologic plausibility
evidence from basic physiologic studies that a causal pathway is credible
T/F: except for description questions, questions that call for a quantitative approach usually concern causal relationships
true
other features of quantitative research designs (3)?
- masking/blinding: when participants aren’t told anything about the study; done to eliminate/decrease bias
- there is a debrief and review after - time frames: researcher has to decide when and how often data will be collected
- location: decisions have to be made about where the data is collected
* quantitative studies consider these every time!!
pretest-posttest design
involves the observation of the outcome (mood) at 2 points in time: before and after the intervention
involves collecting pretest data on the outcome before the intervention and posttest data after it
control group
refers to a group of participants whose performance on an outcome variable is used to evaluate the performance of the experimental group on the same outcome
a control group is used for comparative purposes represents a proxy for the ideal counterfactual
experimental group
the group getting the intervention