research methods Flashcards
what is an experiment?
A testable situation that determines a cause-effect relationship between variables under controlled conditions
what is an independent variable?
the variable that is systematically manipulated by the experimenter in order to measure its effect on the DV.
what is the dependent variable?
the variable that is used to observe and measure the effects of the IV
what is an operationalised variable?
turning the IV and DV into procedures so that it can be manipulated or measured in an experiment
what is a hypothesis?
a statement or testable prediction about the direction of interaction between the IV and DV and the population from which the sample is drawn.
what is a threory?
general explanation of a set of observations or findings of behaviour and/or mental processes that seem to be related
what is a model?
representation of how some behaviours and/or mental processes could, should or do occur
define population
everyone of research interest from which the sample is selected
what is a sample?
the group of people taken from the population to be studied
what is sampling? what is the goal of sampling?
process of selecting participants for a research study to obtain a representative sample of the population from which it was selected
what is stratified sampling?
divides a population into strata (subgroups) based on particular differences in characteristics and then participants are selected from each stratum in the same proportions as they exist in the population
evaluate stratified sampling
adv:
- more representative and unbiased
- allows researcher to sample specific strata for comparative purposes
dis:
- time consuming; requires list of target population for information about population characteristics to be available
what is random sampling?
every individual in the population has an equal chance of being selected for the sample
evaluate random sampling
adv:
- more representative
- generalisations are more likely to have external validity
dis:
- still a chance the sample is unrepresentative
- requires complete list of the target population; time consuming if list is unavailable
what is convenience sampling?
selecting participants who are readily and easily available
evaluate convenience sampling
adv:
- quick, easy, inexpensive
- can be used as a test procedure or gain an indication of possible responses before the actual study
dis:
- biased sample; only those available at the time and location of the study have a chance of being included in the sample
- data obtained can be misleading= results cannot be generalised
what is a representative sample and why is a bigger sample more representative?
- sample that is approximately the same as the population in every important participant variable
- as sample size increases, the characteristics of the sample more closely reflect the characteristics of the population from which the sample was drawn
define allocation
the process of assigning participants to either the experimental group(s) or the control group
what is the purpose of the control group?
not exposed to the IV to provide a baseline of comparison for the experimental group to determine if the IV has had any effect on the DV
what is random allocation?
every participant in the sample has an equal chance of being in the experimental or control group
what is the advantage of random allocation?
- Minimises the effects of individual differences that may occur between participants
- more likely to spread the participant characteristics evenly across the two groups
what are the types of experimental designs?
- independent groups
- matched participants
- repeated measures
what is independent groups design?
different participants are used in each group of the experiment and are exposed to different conditions
evaluate independent groups design
adv:
- if random allocation and sampling is used= helps increase the likelihood of an even spread of participant characteristics between conditions
- no order effects occur as participants only complete one condition
- experiment can usually be completed on one occasion= minimal participant dropout
dis:
- least effective at controlling individual differences between conditions
- often need a larger number of participants to help the spread of participant characteristics
what is matched participants?
each participant is paired with a participant in the other condition according to any important variables relevant to the experiment and then each member of a pair is allocated to either experimental or control group
evaluate matched participant design
adv:
- participant variables are minimised as for every participant there is a similar participant in the other condition
- no order effects as participants only complete one condition of the experiment
dis:
- pairing participants could be time-consuming as pre-testing might be needed
- cannot match participants perfectly on every relevant variable
- loss one participant means loss of the whole pair
what is repeated measures design?
one groups of participants undertake both conditions of the experiment
evaluate repeated measures design
adv:
- participant variables are eliminated as they are kept constant between conditions
- usually fewer participants are required
dis:
- order effects can occur when performing the 2nd condition eg. practice, boredom, fatigue
- participant drop-out rate tends to be higher
what are extraneous variables? why are they not cool and quirky?
- Any variable other than the IV that can cause a change in the DV and therefore affect the results of the experiment in an unwanted way
- makes it difficult for researchers to conclude that any change in the DV was caused solely by the IV and not some other variable
what are confounding variables?
A variable that systematically varies with the IV that has had an unwanted effect on the DV, making it impossible to determine which of the variables has produced the change in the DV.
what are the differences between evs and cvs?
ev:
- May or may not have an effect
Reduces reliability of results
Effect is usually small
cv:
- definitely altered the DV
- Has a similar, although often a greater effect than the IV
- cannot draw a conclusion or make generalisations
- Reduces validity
what are 6 types of EVs and CVs?
EVs:
- individual participant differences
- experimenter variables
- situational variables
- non-standardised procedures and instructions
CVs:
- order effects
- placebo effect
what are individual participant differences? how does it affect the dv?
- The unique personal characteristics, abilities and backgrounds that participants bring with them to the experiment
eg. sex, intelligence, personality characteristics, motivation, emotional state, mood, problem-solving ability, self-esteem, health, cultural background - can affect the way participants responds and their performance in an experiment
what are situational variables? how do they affect the dv?
- any variable associated with the experimental situation itself that may affect the results of an experiment
eg. Background noise, time of the day, testing venues, testing conditions, air temperature - participants in different groups may not be tested under the same conditions and in the same situation= experimenter cannot confidently conclude that any change in the DV is the result of the IV.
what are experimenter effects and why do they affect the dv?
- variables associated with behaviour, expectations, biases, characteristics of the experimenter during the experiment which may result in the participants behaving in a manner different from how they would normally behave= altering the results
eg. The experimenter being tired, their expectations of the outcome of the research, personal issues, health, their gender, how they dress and their attractiveness
what are use of non-standardised instructions and procedures?
Not the same:
Procedures= everything the researcher does in conducting their study
Instructions= what the participants are told
what are order effects?
When performance of one task influences the next task because of the specific order in which the conditions are presented rather than the IV
- cannot determine whether order of condition completed or IV caused the change
eg. Practice effects: repeating a task – can get better or worse in the second condition
-> Boredom, fatigue
Carry-over effects: influences a task has ‘carries over’ to the next task
-> Medication, mood
what are placebo effects?
Any change in a participants behaviour/improvement in symptoms triggered by the belief they are receiving some experimental treatment= respond in accordance with that belief➝ expectation of feeling better
- cannot determine whether the expectations or the IV caused the change
what is a placebo?
- fake/inactive treatment/substance that appears real/resembles the real treatment
how do you control for individual participant differences?
- the type of experimental desgin
- use of random sampling and allocation