Experimental Methods Flashcards
What is an aim
a general statement of what the research intends to investigate, the purpose of the study
What is a hypothesis
- stated at the beginning of a study
- a clear, testable statement that states what is believed to happen/be true
What’s the difference between a directional and non-directional hypothesis?
directional states the kind of difference/relationship between two conditions/participants whereas non-directional simply states that there is a difference
What are variables
- anything that can change or vary within an investigation
- generally used to determine if changes in one thing result in changes in another
what is a null hypothesis
it is a statement of no difference/no relationship; results will be due to chance
What is operationalisation
when you define a variable by specifying a set of observations or behaviours that can be measured
What is standardisation
all participants in a study have exactly the same experience so that individual experience does not cause some participants to engage in the study differently
What are extraneous variables
- variables that have unwanted effects and can come from random error
- researchers try to ensure that extraneous variables have as little effect as possible on the outcome
What is random error and where can it come from
something which can’t be predicted such Pp state of mind
can come from a lack of standardisation
How can researchers work around random error
randomly allocate Pp to different experimental conditions do that the effect of errors can be balanced out
What is a pilot study
it is a small trial run of a research design before the real investigation to ensure everything works correctly and if not can be corrected before completing the actual experiment
What are the 3 types of extraneous variables
Participant Variables;
factors such as Pp age/intelligence
Situational Variables;
factors to do with the experimental setting and environment such as sound/temperature
Experimenter Variables;
changes in the personality, appearance and conduct of the researcher which can affect the experiment
What are confounding variables
come from constant errors
have an effect of the dependent variable making it impossible to say that any effects were directly caused by the IV
What are demand characteristics
they occur when Pp try to guess the aim of the experiment and act accordingly which fails to tell us about real life behaviour as Pp may purposely over/under perform, affecting the DV
How can you reduce demand characteristics
use a single blind procedure which involves Pp having no idea of which condition of a study they are in
What are investigator effects
ways in which researchers unconsciously influence results of research through physical characteristics (age), personal characteristics (tone of voice), bias
How can you reduce investigator effects
double blind technique which is when Pp and investigators are unaware of the aim of the experiment; this prevents researchers unconsciously giving Pp clues
What are control groups
used to ensure results are not due to chance
involves a group who have not experienced any condition so if results are found for the experimental condition then it can be assumed that it is due to the IV
What is counter balancing
ensures that each condition is tested first or second in equal amounts
What are the three main types of experiment
Lab
Natural
Field
What do Lab experiments involve
highly controlled environment using standardised procedures
the IV and DV are precisely operationalised and measured leading to greater accuracy and objectivity, allowing for greater replication and enabling inter-rate reliability
What are disadvantages of lab experiments
experimenter bias where experimenters expectations can affect results and Pp may be influenced by these expectations
low ecological validity as high levels of control create artificial situations so difficult to generalise
Pp may also be aware they are being tested, possibly creating demand characteristics
What do Field experiments involve
performed in a real-world setting where the IV is manipulated and as many variables as possible are controlled
use real scenarios but include confederates to manipulate the IV, this allows for some control whilst improving ecological validity
these relate more to everyday situations so has high levels of mundane realism and can more easily be generalised to real world behaviours and reduce demand characteristics
What are disadvantages of field experiments
more difficult to control extraneous variables so hard to establish causality
conditions are never exactly the same again so it is difficult to repeat experiment in exact same way, meaning results can’t be checked
also may be ethical issues as Pp often are unaware they are being tested and do not provide informed consent
What do natural experiments involve
the researcher does not manipulate the IV, the IV varies naturally and the researchers records the effect on the DV
natural and quasi experiments are often used when it is unethical to manipulate the IV
Random allocation of Pp is not possible
high ecological validity and can be generalised easily
What are disadvantages of natural experiments
it is even harder to control extraneous variables so causality is hard to establish
conditions are rarely the same so unable to repeat experiment; lack of reliability
ethical issues as Pp often unaware they are being tested and do not provide informed consent
Pp not randomly allocated so may be a bias in the sample as Pp variables cannot be controlled
What are the three types of experimental design
Independent groups
Repeated measures
Matched Pairs
What is an independent groups design
different Pp are tested against each other as different Pp are used in each condition and only take part in one condition each
What are the advantages of independence groups
- no order effects
each Pp do one condition each so there are no order effects whereby the order of conditions affects performance
No demand characteristics;
Pp only take part in one condition so there is less chance of them guessing the aim of the study
Time saved;
both sets of Pp can be tested at the same time
What are the disadvantages of Independent groups
- more Pp needed;
as Pp only take part in one condition, twice as many Pp are needed as for repeated measures - group differences
differences in results between the two conditions may be due to participant variables rather than the manipulation of the IV however this is minimised by random Pp allocation to each condition
What is a repeated measures design
each Pp is tested in each condition so Pp are tested against themselves
What are the advantages of repeated measures
- group differences
no Pp variables as Pp are tested against themselves making it easier to establish cause and effect - more data with fewer Pp
fewer Pp are needed overall to produce the same amount of data as an independent groups
What are the disadvantages of repeated measures
- order effects
as different Pp take place in all conditions, there are order effects whereby the order of conditions affects performance
demand characteristics;
due to taking part in both conditions Pp are more likely to guess the aim and act accordingly
Time consuming;
a gap may be needed between both conditioned meaning the experiment takes longer to conduct
What is matched pairs design
this is where Pp are matched on characteristics first such as age
identical twins would ensure maximum matching
What are the advantages of matched pairs
No order effects;
different Pp do one condition each so there are no order effects whereby the order of conditions affect performance
No demand characteristics;
Pp only do one condition so less likely they will guess aim of study
Group differences;
less chance of Pp variables
What are the disadvantages of matched pairs
more Pp needed;
experiment requires more Pp and each Pp takes part in one condition
Matching is difficult;
impossible to match all variables between Pp and unmatched variables may effect results
Time consuming;
lengthy process to match and test Pp
