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40 Cards in this Set
- Front
- Back
True experiment |
Testing whether the independent variable is the cause of any changes in the dependent variable. The researcher has total control over the experiment. |
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In reference to independent variables: Factors Levels Conditions |
Factors: the independent variables Levels: the particular values of an independent variable Condition: the group or treatment (the way the subjects are treated) |
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Two basic elements of good experimental design |
1) The existence of a control group/condition 2) The random allocation of subjects to groups |
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Within-in subject design. What is the basic strategy for achieving control? |
Within-in subject: each subject is exposed to every condition. Counterbalancing (controlling for order and sequence effects by arranging that subjects experience the various conditions in different orders) |
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Order effects |
Changes in a subject's performance resulting from the position in which a condition appears in a experiment. i.e. performance on the 1st condition might be worse than subsequent conditions because the 1st condition acted as a warm-up. Fatigue might also set in if the participant experiences many conditions, or is busy with the experiment for a long period of time. |
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Sequence effects |
Changes in a subject's performance resulting from interactions among the conditions themselves |
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How do you control for order and sequence effects within subjects? |
Counterbalancing for order effects. For sequence effects, arranging that each condition follow every other condition equally often |
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Reverse counterbalancing. When is it ineffective for controlling for order effect? |
Reverse counterbalancing: method of control in which conditions are presented in order the first time, and then in reverse order. It may not control for order effects in an ABCDDCBA experiment because B follows A once and C once, but never follows D or itself. |
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Complete counterbalancing What does it control for? Greatest disadvantage? |
each condition occurs an equal number of times, and follows every other condition an equal number of times Controls for order and sequence within a group of subjects Disadvantage: as you have more conditions you need more orders, and therefore, subjects (i.e. 5 conditions = 120 orders) |
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What is this? |
A latin square. A control procedure in which each subject experiences each condition in a different order from other subjects. Preferred when there are fewer subjects in the experiment Disadvantage: Sequence is not controlled |
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Between-subjects design |
each subjects is only exposed to one level of the independent variable |
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When are between-subject designs preferred over within-subjects designs? |
When a significant reaction would occur between conditions; when a subject can't be used as their own control because of possible carry-over effects |
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3 designs to avoid in research |
One-group posttest only: researcher can't measure the change because no pretest was done. Large threat to validity. Posttest only with nonequivalent control groups: Control group not randomly selected, and they're not equivalent to the experimental group One group pretest/posttest design: even if changes are recorded/measured, a cause can't be determined |
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Factorial designs |
Two or more independent variables (factors) are manipulated simultaneously to determine their separate and combined effects on the dependent variable |
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Advantages of factorial designs |
It is an efficient way of exploring whether or not interdependencies between two or more independent variables exists. There are multiple independent variables and only one dependent variable. |
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How many cells (combinations) are there in 2x3x4 factorial design? |
A 2x3x4 has 3 independent variables with 2, 3, and 4 levels, respectively. It would have 24 cells (or 24 conditions) |
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Main effects
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The influence of one factor on the dependent variable; the effect of a variable averaged over all values of another variable |
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Interaction effects How can one tell graphically if there is an interaction between two variables? |
Interaction effect: when the effect of one independent variable depends on the level of another variable -If the data is graphed, and there are curves that are not parallel, then there is an interaction between variables |
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How to tell interaction effects vs main effects |
If you can explain your study results by only talking about one variable, you have a main effect for that variable. If you MUST mention 2 or more variables to explain the study results, there is an interaction between those variables. |
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What are the common types of interactions in psychological research? |
Antagonist interaction: two ind. variables tend to reverse each other's effects Synergistic interaction: two IVs reinforce each other's effects Ceiling-effect interaction: one variable has a smaller effect when paired with higher levels of a second variable |
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Mixed factorial design |
Includes within-subject variables AND between-subject variables |
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Quasi experiment
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Opposite of true experiment. The research does not/cannot control the assignment of subjects into conditions True = assigning subjects Quasi = selecting subjects |
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When are quasi experiments useful? |
When it is the only possible way to study the impact of a natural event |
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Major weakness of quasi experiments |
Presence of uncontrolled or confounded variables reduces the internal validity |
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What is a non-equivalent control group design? |
Non-equivalent control group - research design having both an experimental and a control group wherein subjects are not randomly assigned |
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What is an interrupted time series design? |
Allows the same group to be compared over time by considering the trend of the data before and after experimental manipulation |
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What are repeated treatment designs? How do they control for confounding variables? |
Treatment is withdrawn, and then presented a second time. Changes between Pretest 1 and Post test 1 should = Pre test 2 and Post test 2 |
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Which quasi-experimental designs can be used with a single-subject? |
Longitudinal study Repeated treatment design |
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What are the common quasi-experimental designs used in developmental psychology? |
Cross-sectional study Longitudinal study Cross-sequential study |
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Advantages and disadvantages of Cross-sectional study |
Advantages: All age groups can be tested at the same time Disadvantages: age is confounded with birthdate (cohort effects are likely) |
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Advantages and disadvantages of Longitudinal study |
Advantages: All the same birthdates, no cohort effects Disadvantages: Takes years to complete, age confounded with time of testing |
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Advantages and disadvantages of Cross-sequential study |
Advantages: Reduces confounding, show effects of time-lag Disadvantages: ? |
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What is a program evaluation? How can quasi-experimental designs be used in program evaluations? |
Program evaluation: A set of techniques for evaluating the effectiveness of a social service program. Quasis are used becuase clients are likely to be assigned to groups for comparison rather than randomly allocated |
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In what ways is scientific communication carried out? |
Publication in professional & academic journal Conventions and conferences Presentations and discussions Laboratory visits Archival publication |
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What are the essential features of a good scientific report? |
Clarity - Say exactly what you mean as directly as possible Brevity - does every word and sentence contribute to the paper? (short & concise) Felicity - a pleasing style (liveliness and grace) |
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Parts of a scientific paper (8) |
Title - indicate contents of the article Authors Abstract - brief summary and key points Introduction - specifies problem & hypothesis Results - Research findings (incl. data, graphs..) Discussion - Brief summary of main results, conclusions, weaknesses, etc. References |
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Plagiarism |
Presenting another person's work as your own |
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Briefly discuss the human biases to which science is subject. |
-Researchers may have to distort findings based on who is funding the research (government parties, corporations, etc.) |
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Discuss the limitations of science in achieving knowledge. |
Limited by technology Limited by our shared view of the world (can't determine value based problems) Science is incomplete and tentative |
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What are the responsibilities of a scientist? |
Find the answer |