Lecture 6 Flashcards
When deciding on participant samples, what are 23main questions we should ask?
- who will participant in my experiment?
- how can I generalize my results to?
- how large should my sample be?
What is a convenience sample?
a sample that is convenient for the researcher.
How might a convenience sample lead to different results than going out into the world to collect participants?
by going out into the community, you can get a different perspective than if you only got university students as a sample. Uni students are often more financially stable, young ,etc . The findings may not generalize. If you go out to the community, you get a more representative sample.
studies investigating norms, beliefs and preferences tend not to generalize very far because culture really shapes those things.
if what you are studying is assumed not specific to people of certain cultures ages etc, then it shoudl be fine for you to use convenience samples.
What is external validity?
whether or not the results can be generalized to people of a different group
How large should a sample be if using random assignment?
we should consider if we will have the statistical power to observe a relationship to
How does the number of participants effect risk of participant variables preventing the ability to observe a relationship?
with smaller numbers of participants the risk is higher and the risk decreases as participants increase. as your study size gets larger, participant variables will be es likely to have an impact Note that the risk never gets to zero, instead the graph depicting this relationship would asymptote and level off. AKA at some point the number of participants has diminishing returns.
What is the size of effect we observe a ratio of?
manipulation strength and noise
is noise the same as confounds?
noise is not the same as confounds because confounds have to be systematically different across conditions. We are using random assignment so this isn’t a confound.
What do we mean by noise?
unpredictable behaviour or random things that could change participant behaviour
What do we mean by manipulation strength?
the way we operationalize our variable
Are stronger manipulations easier to see?
yes
to controlled experiments reduce noise?
yes.
does control have an affect on our ability to see effects?
yes. the more we can control things like distractions, the more we can see the effects if they are there.
Should we try to investigate strong relationships first? Why?
yes.
More likely to determine if your hypothesized relationship is present
Follow up with more subtle operational definitions of IV
What is a straightforward manipulation?
Straightforward manipulations:
- Simply showing participants research stimuli
- Survey research, most computer-based research
- Advantages: Simple; cost-effective; deception not needed
What is a staged manipulation?
Staged manipulations:
- Elaborate “play” to generate psychological situations
Advantages:
- Experimental realism – Ss experience the situation as engaging!
- Generalizability beyond lab will usually be high, good external validity
What is experimental realism?
the degree the which the person is experimentally engaged.
What is mundane realism?
the resemblance to an everyday situation
What are the 3 ways of studying dependent variables?
- Self-reports
- Behavioral
- Physiological
What are the 2 general classes of reports?
Two general classes: § Direct
- “Are you feeling anxious?” (direct self-report)
- “Make as many free throws as you can” (direct behavioral) § Indirect
- Measure heart rate (indirect physiological)
- Covertly observe participant behavior (indirect behavioral)
Do different measures impose different psychological constraints? What can you do to prevent this?
yes.
Recommendation: Use multiple methods/measures
§ Is the relationship true under different conditions?
What is the primary use of pilot studies? What are the three questions you should seek to answer? WHat is a pilot study not meant to answer?
Debugging
- Are there logistical problems you didn’t foresee? Probably!
- Is the data you’ll be collecting useful? § Ceiling effects or floor effects?
- Is the psychological experience as you expect? § Manipulation check
NOT:
- Is the hypothesis correct/’working’?
- Is the data “right” or “wrong”?
What is demand characteristic? Example?
Is demand characteristic a confound?
Participant awareness of hypotheses generally leads to compliance
Example: Does exercising increase happiness? § IV: Do not exercise vs. exercise 7x this week
DV: Self-reported happiness
yes.
What are 3 solutions to demand characterstic?
Solutions to demand characteristics:
1. Between-subject designs:
- Participants now only see one experimental condition
- Not foolproof, especially when working with highly intelligent and social participants
- Filler:
- Additional experimental procedures, items, or delays that obscure the hypothesis - Placebo or expectancy manipulations
- Create identical psychological experience, with and without the active ingredient
What could be the effect of discussion between participants in a between subjects design?
discussions between participants can reduce internal validity by introducing demand characteristics
What is the best solution to demand characterstics?
blinding
What is blinding? What are the 2 different types?
Blinding: Fully obscuring either hypotheses and/or the experimental manipulation
- Single-blind design: Participants are unaware of their condition (e.g., placebo vs. treatment)
- Double-blind design: Both participants and experimenter are unaware
