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Flashcards in Experiments Deck (35)
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1
Q

What is the purpose of experiments?

A

To examine and test causal relationships or ceteris paribus relationships

2
Q

What are the rules of causality?

A
  • To establish that variable X causes Y, all there conditions must be met:
    1. Both X (cause) and Y (effect) should covary
    1. X should precede Y. There must be a time sequence in which the two occur.
    1. No other factor should possibly cause the change in the outcome Y. Other variables that might covary with Y must be controlled for
3
Q

What kinds of variables are there in experiments?

A
  • Independent
  • Dependent
  • Confounding variable
  • Extraneous variable
4
Q

What are independent variables?

A
  • X

- Cause

5
Q

What are dependent variables?

A
  • Y

- Effect

6
Q

What are confounding variables?

A
  • When there is an alternative explanation beyond the experiment variables for any observed difference in the dependent variable
  • Effects the DV
  • DOES effect
7
Q

What are extraneous variables/

A
  • Variables that naturally exist in the environment that may have some systematic effect on the V
  • Could affect the DV but has been controlled for so it doesn’t
  • MAY effect
8
Q

What are the two essential aspects of experiments?

A
    1. Manipulation of the independent variables
      - The changes in X cannot occur naturally, they have to be deliberalty created, manipulated or arranged by the experimenter
    1. Control of the extraneous variables
      - The method can only be used when subjects and conditions to be studies can be practically and ethically manipulated by the researcher
9
Q

What is the method to conducting experiments?

A
  • Identify the causal factors
  • Plan and Administer the manipulations
  • Plan and apply controls
  • Observe and Measure the DV
10
Q

What are treatments in experimentation?

A
  • Manipulations of the IV are also known as treatments which are administered to the experimental groups whereas control groups do not receive these treatments
11
Q

What are the ways in which the IV can be manipulated?

A
  • Presence vs Absence technique
  • Amount technique
  • Type technique
12
Q

How are controls planned and applied in the experimentation method?

A
  • Proper sampling techniques
  • Standardisation of conditions
  • Controlling EVs and CEs
13
Q

How can EVs and CEs be controlled for?

A
  • Confounding effects and extraneous variables can be minimised through good sampling
  • Randomisation
  • Matching groups
14
Q

What is randomisation in experimentation?

A
  • For controlling for the EVs and CEs
  • Involves randomly assigning subjects to experimental and control groups
  • Doing so distributes the effects of counfounding variables across groups equally
  • Any errors caused by say age or gender are now more or less similar across groups
15
Q

What are matching groups in experimentation?

A
  • For controlling for the EVs and CEs
  • More precise strategy
  • On the basis of confounding variables
  • e.g. the effects of gender and age can be distribute across groups
  • The risk is that we may fail to match some critical factors across groups
16
Q

What is the treatment effect?

A

In observing and measuring the DV, the difference between pre-testing and post-testing

17
Q

What are the types of experimental design?

A
  • Two randomised groups design (classic design)
  • Two matched groups design
  • Two within-subjects groups design
  • Multiple Groups designs
  • Facotrial designs
18
Q

What is the two randomised groups experimental design (classic design)?

A

Random assignment of participants are made to the experimental and control groups

19
Q

What is the two matched groups experimental design?

A

Participants in the experimental and control groups are matched with one another in terms of potential EVs

20
Q

What is the two within-subjects group experimentals design?

A

Participants in the experimental and ctonrol groups are the same people, measures before and after the treatment - the ultimate in matching

21
Q

What is the multiple groups experimental design?

A

IV has more than 2 conditions; participants can be randomly assigned, matched or repeated across the conditions

22
Q

What is the factorial experimental design?

A

More than one IV is investigated, allows experiments to test a more complex causal hypothesis as DVs can have multiple causes; allows exploration of interactions effects of IVs too

23
Q

What are the two types of experiments?

A
  • Laboratory
    • Contrived but standardised environment
    • When manipulations and controls are introduced to establish cause-effect relationship in an artificial setting
  • Field
    • Conducted in a natural setting, often for a longer period of time
    • Not possible to control for all extraneous variables in the field because it may not be possible to assign subjects to groups or match them
24
Q

How can the internal validity of an experiment be measured?

A
  • Did the experiment measure what is set out to do
  • The ability of an experiment to establish whether the experimental treatment (IV) was the sole cause of changes in a DV
  • Experiment is invalid if there are rival hypotheses or alternative explanations for the results
25
Q

How can the external validity of an experiment be measured?

A
  • Can the findings be applied to other situations outside the experimental situation
  • The extent to which the results found are generalisable to actual field or organisational settings
26
Q

What is true of the validity of the different types of experiments?

A
  • Lab experiments have high internal validity but low external validity compared to field experiments
  • To ensure both types, some researches first test causal relationship in a laboratory setting, and then examine whether such relationship are generalisable to the field setting
27
Q

What threats to experimental validity are there?

A
  • History effects
  • Maturation Effects
  • Testing Effect
  • Instrumentation Effect
  • Selection Bias Effects
  • Demand Effects
  • Hawthorne Effect
  • Morality or Attrition
28
Q

What is the history effect threat to experimental validity?

A
  • Specific events that occur while the experiment is in progress that could impact on the DV, but are beyond the control of the experiementer
  • e.g. a natural disaster or an economic downturn occurs; new laws are passed; the company downsizes
29
Q

What is the maturation effect threat to experimental validity?

A
  • The passage of time over the course of the experiment can influence the DV
  • Subjects can get tired, gain experience, get bored, grow older and these processes can affect the DV
30
Q

What is the testing effect threat to experimental validity?

A
  • Mere exposure to the pre-test may influence results of the post-test
  • Participants become sensitised to the post-test
31
Q

What is the instrumentation effect threat to experimental validity?

A

Changes in the measuring instruments between pre-test and post-test can also influence the DV

32
Q

What is the selection bias effect threat to experimental validity?

A
  • Improper selection of subjects for the experimental or control groups
  • Subjects in experimental and control groups can not be matched
33
Q

What is the demand effect threat to experimental validity?

A
  • When participants pick up cues during an experiments and modify their behaviours
  • Some may try to please the experimenter and give her they thing she wants/expects
  • Others might mess it up for the experimenter
34
Q

What is the Hawthorne effect threat to experimental validity?

A

The act of observation causes people to act differently from normal

35
Q

What is the morality or attrition threat to experimental validity?

A
  • Composition of the groups can change when participants drop-out or withdraw
  • This makes it difficult to compare experimental and control group