Types of experiments Flashcards
(22 cards)
Describe the features of a lab experiment
strength and limitation
These are conducted in special environments where variables can be carefully controlled, participants are aware they are taking part in an experiment but they may not know the true aim of the study.
Limitation -This awareness of being in an experiment contributes to the contrived nature of these studies, also less like daily life, the environment may also seem artificial and uncomfortable
Strength- high internal validity , good control over all variables
Describe the features of a field experiment strength and limitation
Conducted in a more natural environment e.g a field The same as a lab experiment, the IV is still deliberatley manipulated by the researcher and the researcher measures the DV.
Strength- participants are not usually aware they are participating in an experiment meaning their behaviour is more natural
Limitation-Lower internal validity, harder to control extraneous variables
Describe what a repeated measures design is
strength and limitation
All participants receive all levels of the IV for example each participant does the task with the TV on and then a week later they do it with the TV off and we will compare the DV on both tests
Strength- Since each participant provides data for multiple conditions, fewer participants are required to achieve the same level of statistical power compared to independent groups designs
L- Participants may do better on second test as they have practise effects or do worse due to boredom effects
Describe what an independent groups design is
strength and limitation
Participants are placed in separate groups and each group does one level of the IV e.g group A may do task with the TV on and group B will do it with it off and the DV will be compared between them both
Strength- avoid practise effects as each participant only does one condition
L- Researchers cant control effects of participant variables, one group may have a better memory than the other etc acting as a confounding variable
Describe what a natural experiment is and give strengths and limitations
Conducted when it is not possible for ethical or practical reasons to directly manipulate an IV
- Strength enables researchers to study real problems
Limitation, cannot demonstrate causal relationships as Iv is not directly manipulated
Opportunity sample with strengths and limitations
- Recruit those who are most convenient or most avainable
S- takes less time to locate sample
L-Sample drawn from a small part of population, location of a person may indicate their characteristics
Random sample with strengths and limitations
Each item has an equal chance of being selected
e.g random number generators , give number for every member then use excel, RAND(100) to get random number
S- unbiased
L-List and contact of members takes time
Stratified sample with strengths and limitations
Subgroups are identified in population e.g age groups
Ppt are obtained from these groups to their occourence in population, random technique
S- more representative as they are proportional
L- time consuming to get sub groups
Systematic sample with strengths and limitations
Predetermined system to select ppt, selecting every nth person from a phone book
S- unbiased objective system
L- Only random if number is selected to start with this person , then select every nth person
Voulunteer sample with strengths and limitations
Advertised in a newspaper or on internet
S-Acesss to a variety of ppt, sample is more representative and unbiased
L- Some ppt are more highly motivated than others , have alot of time so sample is biased
Matched pairs with strengths and limitations
Use 2 groups of ppt, match participants on key characteristics believed to affect performance on the DV
One member is allocated to one group and the next member is allocated to a diff group
S-No practice effects as each participant does one condition
L-Time consuming to match participants on key variables, large group needed
Naturalistic observation with strengths and limitations
Behaviour is studied in a natural situation where everything is left as it normally is, researcher doesnt intefere in any way
-realistic observation of spontaneous behaviour, high in ecological valdidity
l-little control,something unknown to observer may acount for behaviour observed
Controlled observations with strengths and limitations
Some variables are regulated by the researcher , including naturalness of envrironment and behaviour, ppt know they are being studied
s - observer can focus on particular aspects of behaviour
l-behvaiour unrepresentative
Overt/ covert observation with strengths and limitations
Overt-ppt are aware of observations, effect on naturalness of behaviour of ppt
s-ensures informed consent
l- unrepresentative behaviour
covert-ppt are unaware of being observed
s- natural behaviours shown
argued that consent is not valid
Counterbalancing
Ensures that each condition in a repeated measures design is tested first or second in equal amounts
Use two conditions e.g A is test done in morning and B is test done in afternoon
Then divide participants into 2 groups, group 1 does a then b and group 2 does b then a , comparison will be made for each participant on their performance on 2 conditions
Extraneous variable
Do not vary systematically with the IV and therefore do not act as an alternative IV, but pose an effect on the dependent variable
Make it more difficult to detect a significant effect
Internal validity
External validity
Internal- focuses on the truthfulness of the results within the study, ensuring that the observed effect is due to the manipulated variable and not other factors. done by controlling extraneous and confounding variables
External-External validity refers to the extent to which the results of a study can be generalized to other populations, settings, situations, and measures. concerned with ecological validity ( where the research has taken place may not be able to generalise to other settings), population validity( one group of people cant be generalised to other people) historical validity( time research was taken place is not generalised to other times, different factors affect people at diff times)_
Reliability
The consistency of a measurement or a test. It indicates how consistently a method measures something, meaning that if you apply the same method under the same conditions, you should get the same results.
Confounding variable
Variable under study which is not the IV but varies systematically with the IV, changes in the dependent variable may be because of the counfounding variable rather than the IV
Demand characteristics
Scoail desirability
evaluation apprehension
investigator effects
Demand characteristics refer to cues in a study that might reveal the research objective, leading participants to behave in a way they think is expected.
SD-occurs when participants respond in ways that they believe are socially acceptable regardless of their true feelings or beliefs.
Eval app- refers to the anxiety or concern that participants may feel about being evaluated by others, potentially leading to changes in behavior.
I E- occur when a researcher
unintentionally, or unconsciously influences the outcome of any research they are conducting. C or E variable
Measures of central tendency with examples
Middle values in a set of data, avgs calculate a typical value for a set of data
e.g mean median and mode
Measures of dispersion with examples
How spread out the data is , range and sd above and below the mean
