experiments Flashcards
what is a laboratory experiment
the independent variable is manipulated by the researcher and the experiment is carried out in a laboratory or another controlled setting away from participant’s normal environment
what is a field experiment
the independent variable is manipulated by the researcher but this time the experiment is carried out using participants in their normal surroundings
what is a quasi experiment
independent variable is naturally occurring, not manipulated by researcher
advantages and disadvantages of lab experiments
-reduces extraneous variables
-internal reliability as lots of controls
-low ecological validity
-more costly
advantages and disadvantages of field experiments
-ecological validity
-less costly
-more extraneous variables, low construct validity
-low internal reliability
advantages and disadvantages of quasi experiments
-high ecological validity
-helps study variables we can’t manipulate
-participant variables may influence results
what is repeated measures design
involves using the same people in each condition
what is independent measures design
involves using different people in each condition
what is matched participants design
involves using different people in each condition but matching them based on similar characteristics to make them as similar as possible
advantages and disadvantages of repeated measures design
-remove participant variables
-fewer participants needed overall
-demand characteristics
-order effects
advantages and disadvantages of independent measures design
-reduce demand characteristics
-no order effects
-more time consuming to collect larger sample
-participant variables
advantages and disadvantages of matched participants design
-reduced effect of participant variables
-no order effects
-no demand characteristics
-cannot control extraneous variables by perfectly matching participants
-more time consuming to find larger sample
what is a participant variable
age, intelligence, motivation, skill, experience, gender
how can participant variables be controlled
repeated measures/ matched participants design
independent measures- allocate participants to conditions randomly to evenly distribute participant variables
what is situational variables
order effects- if doing same activity twice participants may be better at it because of practice / worse because of boredom
how to control situational variables
matched participants/ independent measures design
repeated measures should be counter balanced, participants split into 2 groups, one does Task A first then B, one does B first then A
what are environmental factors
time of day, temperature, noise
how can environmental factors be controlled
impose controls on the experiment to ensure there are as few differences as possible
what are demand characteristics
cues in an experiment that communicate to participant what is expected of them and which may unconsciously affect the behaviour of participants
how to control demand characteristics
do not tell participants aim of investigation (single blind procedure)
why might studies be double blind
to reduce risk of researcher effects eg researcher being more encouraging
eliminate researcher bias eg holding onto the data they expected / choosing specific participants
what is a hypothesis
a precise testable statement of the relationship between two variables
what is a two tailed alternative hypothesis
IV will have significant effect on DV but it does not predict the direction the effect will go in
eg: rainy weather has a significant effect on people’s levels of happiness
what is a one tailed hypothesis
IV will have significant effect on DV in a specific direction
eg: men who have beards are perceived as significantly older than clean shaven men
how do you operationalise a hypothesis
be SPECIFIC
old age: give age range
sporty people: sports for >2 hours
strengths and weaknesses of self selecting sampling
-consent covered
-less researcher bias
-less likely to withdraw
-time consuming
-harder to obtain large sample so not representative
strengths and weaknesses of opportunity sampling
-less time consuming
-easier to get large sample
-researcher bias
-participants not interested
strengths and weaknesses of random sampling
-representative of target population as everyone has equal chance of being selected
-outliers
-may not be willing to take part
strengths and weaknesses of snowball sampling
-easy to obtain sample quickly
-participant variables
-not able to generalise: family and friends have similar characteristics
what are the 4 ethical considerations
respect
competence
responsibility
integrity
respect ethics
-informed consent
-right to withdraw
-confidentiality
competence ethics
researchers should not give advice for things they aren’t trained on
responsibility ethics
-protection from harm
-debrief
integrity ethics
-deception
what is primary data
data that is collected by researcher directly
what is secondary data
data that already exists which can be used in other research methods e.g crime statistics
strengths and weaknesses of qualitative data
-rich in detail
-helps understand context
-holistic
-subjective due to researcher bias
-difficult to generalise (case study)
-time consuming
advantage and disadvantage of using mean
-involves all data
-includes outliers which may skew result
-give us decimal figures so data more complex
advantage and disadvantage of using median
-discounts outliers so not skewed
-does not include all data collected
-may be decimal - more complex
advantage and disadvantage of using mode
-easy to calculate
-always a whole number
-can be done with qualitative data
-may be more than one mode
-doesn’t include all data
advantage and disadvantage of using range
-easy to calculate (only 2 numbers)
-helps identify outliers
-ignores central tendency
-sensitive to outliers
advantage and disadvantage of using variance
-takes all data into account
-identifies patterns in data
-complex to calculate
-sensitive to outliers
advantage and disadvantage of using standard deviation
-takes all data into account
-integral to statistical tests
-time consuming
-more difficult to calculate than range
