Week 9 Flashcards
Lab experiment meaning
Experiment in artificial environment
Field experiment meaning
Experiment in a natural setting (everyday, real-life environment)
When Lab/Field experiments are suitable
-Number of independent and moderator variables is limites
-At least on of these variables can be maniputaled
When Lab experiment is better than field
When researchers want maximum control over the research environment to rule out alternative explanations. (Results in higher internal validity)
When Field experiment is better than Lab
-When essential to measure real-world behavior in real-world situations, i.e., when high external validity is crucial
-When studying long-term effects of manipulation(s)
Experimental condition meaning
A modified changed form of a variable (for the experiment)
Treatment groups
Groups which are not control group
Within-subjects design
each subject (participant) is presented with all levels of the independent variable
[to what extent a monetary bonus (the IV) increases employees’ work motivation (the DV). You give all employees in a company a bonus, and you compare their work motivation at time t-1 (before the bonus) with their work motivation at time t (after the bonus)]
between-subjects design
different groups of subjects are assigned to different levels of the independent variable
[to what extent a monetary bonus vs. a non-monetary bonus (the IV) increases employees’ work motivation (the DV). You randomly allocate participants to conditions, ask them to work on a task, and make sure that the only thing that differs between the groups is that you give a monetary bonus to group 1 and a non-monetary bonus to group 2.]
2 Types of between-subjects design
- Posttest-only design - Subjects are randomly assigned to the levels of the independent variable. The dependent variable is then measured once. [Measure work motivation only after the bonus]
- Pretest/posttest design - participants are randomly assigned to the levels of an independent variable. The dependent variable is measured twice: once before and once after exposure to the independent variable. [Measure work motivation before giving bonus and after the bonus.]
mixed factorial design
one independent variable is manipulated as between-subjects, and one independent variable is manipulated as within-subjects
How to demonstrate validity of measured variables
-provide precedence (has this measure been used before)
-Using sound arguments (why does this measure capture the variable)
For manipulated variables: - Manipulation checks
Manipulation check meaning
Test used to determine the effectiveness of manipulation in an experimental design and ensure that the participants understood the maniplation as the researcher intended
3 types of threats to internal validity
- Design confounds - poorly designed and another variable happens to vary systematically along with the independent variable
- Demand effects - participants guess the purpose of the experiment and change their behavior accordingly
- Experimenter bias - experimenters (intentionally or unintentionally) influence the data, participants, or results because they can’t stay completely objective
Maturation effect meaning and solution (in design confound threat to internal validity)
becoming tired, bored, or hungry, or learning and forgetting things over time simply because time passes
Solution: introduce control group that is measured at the same time but is not exposed to the treatment
History effect meaning and solution (in design confound threat to internal validity)
external factors systematically affect most members of the treatment group at the same time as the treatment itself [Significant corporate restructuring happening within a 6 month research period at the same time might influence research on work stress]
Solution: Introduce control group
Testing effect meaning and solution (in design confound threat to internal validity)
a change in participants’ responses as a result of taking a test more than once
Solution: Control group
Instrumentation effect meaning and solution (in design confound threat to internal validity)
measurement instrument is changed during the course of the study [Switching survey formats]
Solution: Maintain measurement instruments the same throughout the study. Control group if unavoidable as well
Selection bias effect meaning and solution (in design confound threat to internal validity)
characteristics of participants in one group are systematically different from those in another group
Solution: Random selection to groups
Mortality effect / Attrition effect meaning and solution (in design confound threat to internal validity)
participant drop-out before the end of the study
Solution: checking whether dropouts differ from completers
Demand effects meaning and solution
participants guess the purpose of the experiment and change their behavior accordingly
Solution: single-blind experiment can be conducted. In a single-blind experiment, participants are unaware of which group they have been assigned to until after the experiment is completed
Experimenter bias effect meaning and solution
experimenters (intentionally or unintentionally) influence the data, participants, or results because they can’t stay completely objective
Solution: double-blind study, neither the participants nor the experimenters know which participants are in the treatment group and who is in the control group
Internal and External validity of Lab vs Field experiments
Lab: High internal (control for confounding variables); Low external validity (applicable to real life situations)
Field Low internal; High external validity
Random sampling vs Random assignment
Random sampling is the random selection of subjects from a population. It, therefore, pertains to the study’s external validity.
Random assignment involves randomly assigning each subject in the sample to the experimental conditions. Therefore, it pertains to the study’s internal validity.
