Experiments Flashcards
What do experiments aim to find
cause and effect
IV
variable being changed
DV
variable being measured as result of IV
What are the 2 conditions of an experiment called?
Experimental condition and Control condition
What are the 3 experimental types
Laboratory
Field
Quasi
Explain lab experiments
IV manipulated by researcher in a controlled setting away from P normal environment
Explain field experiments
IV manipulated by researcher in natural settinf
Explain quasi experiments
IV naturally occurring
Advantages of lab experiments
Less EVs
High internal reliability (standardised)
High construct validity
Disadvantages of lab experiments
Demand characteristics
Lacks ecological validity
Time consuming
Expensive
Advantages of field experiments
Higher ecological validity
P will act naturally
Disadvantages of field experiments
Less control
Hard to repeat exactly
EVs
Advantages of quasi experiments
High ecological validity
P will act naturally
Study variables we can’t manipulate
Disadvantages of quasi experiments
Less control
Low internal reliability
P variables
Hard to conduct
What is validity
If research accurately measures what it intends to measure
What’s ecological validity
the extent to which the study represents a real life situtaion
What’s population validity
the extent to which the sample is generalisable
What’s construct validity
where the test has been shown to measure what it’s supposed to be testinf
What’s internal reliability
whether the procedure is standardised and replicable
What’s external reliability
whether the study has enough participants to establish a consistent effect
What are the 3 experimental designs?
Repeated measures
Independent measures
Matched participants
Repeated measures
sample people in each condiiron
Independent measures
different people in each condition
Mather participants
different people in each condition but attempt to make participants as similar as possible on certain characteristics
-done by testing, pairing and splitting them
Advantages of repeated measures
No participant variables
Fewer p needed
Easy
Disadvantages of repeated measures
Time consuming
Could guess aims (demand characteristics)
Would have more practise on 2nd try
Order effects
Advantages of independent measures design
Easy
Wont guess aims
No order effects
Disadvantages of independent measures
Could have p variables
Need more p
Advantages of matched participants
Few p variables
Wont have demand characteristics
Reduces order effects
Disadvantages of matched participants
Effort to match them
Time consuming
Cant control all EVs
What are participant variables
characteristics of p that may influence results
What are situational variables
any feature or research situation which may influence a participants behaviour and therefore the results
Ways to control participant variables
Repeated measures or matched participants designs
For independent groups allocate randomly to evenly distribute variables
Ways to control situational variables (order effects)
Have different people in each condition
If repeated measures, counterbalance (one group does A then B and the other does B then A)
Ways to control situational variables (environmental factors)
Controls
Ways to control situational variables (demand characteristics)
Don’t tell p the aim (single blind procedure)
What is double blind procedure
neither participants nor people carrying out research know the aims
What’s a hypothesis
A precise testable statement of relationship between 2 variables
What’s an alternative hypothesis
Predicts the IV will affect the DV
Give an example of an alternative hypothesis
There will be a significant difference in… when…
What’s a null hypothesis
Predicts there will be no effect of the IV on the DV
Give an example of a null hypothesis
There will not be a significant difference in… when…
What’s a two tailed hypothesis
Predicts the IV will have a significant effect on the DV but doesn’t predict the direction
What’s a one tailed hypothesis
Predicts the IV will have a significant effect on the DV and the direction of this effect
What’s operationalising
making variables physically measurable or testable
What’s a target population
group of people researcher is interested in studying
What are sampling methods
different ways in which researchers can obtain a sample of people from within the target population to take part in the study
what’s a sample
group of participants used in the research
Describe self selecting
people volunteer to take part
Describe opportunity sampling
selecting those most readily available at a given time and place
Describe random sampling
Each member of target population has equal chance of selection
Describe snowball sampling
P are asked to contact friends and family and ask if they’ll participate
Advantages of self selecting
easy to obtain
already have consent
no researcher bias
Advantages of opportunity sampling
easy to obtain
good way to get target pop
Advantages of random sampling
all equal chance of selection
representative of target pop
Advantages of snowball sampling
easy
weaknesses of self selecting sampling
unrepresentative sample
expensive if money is incentive
small sample
weaknesses of opportunity sampling
unrepresentative sample
researcher bias
weaknesses of random sampling
outliers
hard to ensure was equal
may not want to take part
effort
weaknesses of snowball sampling
participant variables
cant generalise (similar characteristics)
