Psychology- Experimental Methods

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  • Created by: Evie :)
  • Created on: 13-10-21 11:09
What is a lab experiment?
One in which there needs to be an IV and DV
The IV can be randomly allocated to participants
It is in a controlled environment
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Strengths of a lab experiment
- strict control and standardisation, meaning that the experiment can be repeated
- strict control also means that a relationship can be established between the IV and DV
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Weaknesses of a lab experiment
- The setting is artificial, which does not mirror real like ( lacks ecological validity)
- Participants know they are being studied, which can affect their behaviour and increase demand characteristics
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What is a field experiment?
One in which there is an IV and DV
The IV can be randomly allocated to participants
Not in a controlled environment
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Strengths of a field experiment
- greater validity, as participants don't know they are in an experiment
- Higher ecological validity as research is taking place within the real world
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Weaknesses of field experiments
- consent is not always acquires and participants may experience distress
- less control over extraneous variables
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What is a quasi experiment?
one in which the IV is naturally occurring (age, gender)
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strengths of quasi experiments?
- Greater ecological validity, as it enables the study of real problems
- allows for research where the IV cannot be manipulated
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weaknesses of quasi experiments?
- participants are aware they are being studied, can increase demand characteristics
- IV's are difficult to replicate as events may not happen again
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What are extraneous variables
variables other than the dependent variable, which could affect the independent variable
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What are the types of extraneous variables
situational variables- noise, temperature, varying instructions
demand characteristics- participant acting different, when realising aim
experimenter bias- they affect results conscious or unconscious
participant variables
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what is a repeated measures design?
when one group of participants take part in both control and experimental tasks
the participant is tested against themselves
testing to see if the dependent variable influences the independent variable
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strengths of a repeated measures design
- less participants are needed/ less time consuming and cheaper
- control of participant variables as people take part in both tasks, reducing bias
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Weaknesses of a repeated measures design
- order effects, (e.g, lack of energy after first task) which influences how a person performs
- risk of demand characteristics
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what is an independent measures design
- when different participants are used in 2 different groups
- each participant only does one condition or performs one task
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what are the strengths of using an independent measures design
- avoidance of order effects as participants only perform one task, so less likely to get better or worse with practice
- less likely to be demand characteristics if only in one task,/ less likely to figure out aim
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What are the weaknesses of using an independent measures design
- there could be participant variables, resulting in bias
- the sample is large/ time consuming and expensive
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what is a matched pairs design
one which consists of two separate groups, matched on important characteristics
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strengths of a matched pairs design
- order effects are avoided as participants only perform one task
- participant variables are avoided, as matching process eliminated differences between groups
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weaknesses of matched pairs design
- requires a big sample/ time consuming and expensive
- it is not practical, as finding identical/ matching characteristic pairs is difficult
- tiredness or motivation levels can affect results
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What is standardisation
using a standard procedure for all participants and controlling variables
it is necessary to avoid extraneous variables, which would affect the results
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what is memory
The ability to store information presented to us and to be able to use that information at a time in the future to influence our behaviour.
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what is a snowball sample
when the experimenter approaches a member of the target population and asks them to take part
- They then recruit other members until the relevant number of participants is reached
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strengths of snowball sampling
- can find people easily if participants ask people they know, as they are more likely to participate
- a desired group can be found if a researcher approaches someone of interest and they bring their friends/family, as they will have similar interests
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weaknesses of snowball sampling
- can be hard to find people
- not likely to be a good cross section from the population, as people asked bring people they know ( relatives) and results may be biased
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what is a self-selecting/ volunteer sample?
One which consists of participants becoming part of a study because they volunteer when asked or in response to an advert
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strengths of a self- selecting sample
- people are committed if they respond to an advert or volunteer because it shows they're willing/ less likely to drop out
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weaknesses of a self- selecting sample
- people can't always be relied upon to attend
- the sample is biased, as participants will be highly motivated ( capable of the study) if they volunteer and there will not be a wide range of results
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what is opportunity sampling?
(most popular/ used)
It consists of people who are available at the time when the study is carried out
Also people are used if they fit the criteria a researcher is looking for
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strengths of opportunity sampling
- Can gather people quickly if you are with people you know as they are more likely to participate (e.g, family in household)
- Very easy method, as you use the first people you find
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weaknesses of opportunity sampling
- biased as sample is drawn from only a small part of the target population
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what is random sampling?
- It involves identifying everyone in the target population, then selecting the number of participants you need in a way that gives everyone in the pop an equal chance of picking
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strengths of random sampling
- It is unbiased as all members of the population have an equal chance of selection
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weaknesses of random sampling
- random picking methods (e.g, generators) may not always represent the target population as they select people
- This takes more time and effort
- Results can be biased as not all people randomly selected will agree to participate, (small sample)
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What is an alternate hypothesis?
One in which states an outcome of research, relating to the variables
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What is a null hypothesis?
One which suggests that any difference or effect from the study occurs by chance and not because of the variables which have been manipulated
E.g, There will be no difference in DV between IV condition 1 and IV condition 2
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What is a one-tailed hypothesis?
One which is directional, stating one possible outcome
E.g, IV condition 1 will be more/less DV than IV condition 2
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What is a two tailed hypothesis?
One which is non directional, with 2 possible outcomes
E.g, There will be a difference in the DV between IV condition 1 and IV condition 2
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Other cards in this set

Card 2

Front

Strengths of a lab experiment

Back

- strict control and standardisation, meaning that the experiment can be repeated
- strict control also means that a relationship can be established between the IV and DV

Card 3

Front

Weaknesses of a lab experiment

Back

Preview of the front of card 3

Card 4

Front

What is a field experiment?

Back

Preview of the front of card 4

Card 5

Front

Strengths of a field experiment

Back

Preview of the front of card 5
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