Experimental Research Methods Flashcards
What are experimental research methods?
The manipulation of an independent variable to measure the effect on the dependent variable
What is a research aim?
A general statement about what the researcher intends to investigate
What is a hypothesis?
A statement that clearly states the relationship between variables
What is a directional hypothesis?
Researcher makes clear the sort of difference that is anticipated between two conditions/groups (more, less, higher, lower etc.)
What is a non-directional hypothesis?
State there will be a difference, but don’t specify the direction
What is the independent variable?
What the researcher manipulates
What is the dependent variable?
What the researcher measures
What does operationalising variables mean?
Clearly defining variables in terms of how they can be measured
What is the experimental condition?
- where the research takes place
- refers to the group of participants who are exposed to the IV
What is the control condition?
- equivalent to the experimental condition, except for the IV
- IV is absent or held constant
What are extraneous variables?
Affects all conditions so results should not be affected as conditions remain constant
What are confounding variables?
Don’t affect all conditions so may affect the results of the study as we can’t be sure what caused the changes in the DV
What are demand characteristics?
Any cue from the researcher or research situation that may be interpreted by participants as revealing the purpose of the investigation, and thus may lead to a participant changing their behaviour
What is the ‘please-u’ effect?
When pp act in a way that they think is expected, and over perform to please the experimenter
What is the ‘screw-u’ effect?
When pp may deliberately under-perform to sabotage the results of the study
What are investigator effects?
Any effect of the investigator’s behaviour on the research outcome
What is randomisation?
The use of chance in order to control for the effects of bias when designing materials and deciding the order of conditions
What is standardisation?
Using exactly the same formalised procedures and instructions for all participants in a study
What is experimental design?
Refers to the way in which participants are arranged in a study
What are the 3 types of experimental design?
- independent groups
- repeated measures
- matched pairs
What is independent groups design?
When each participant only experiences 1 condition of the experiment and then the groups would then be compared
Give one strength of independent groups design
Order effects are not a problem
Give one weakness of independent groups design
The pp may have individual differences which affect the change in the DV more than the IV does
What is repeated measures design?
All participants experience all conditions of the experiment, then each set of data are compared to see if there was a difference
Give one strength of repeated measures design
Fewer participants are needed
Give one weakness of the repeated measures design
Order effects may arise due to participants becoming bored or fatigued from doing multiple tasks, which could negatively affect performance on the second task
What is the matched pairs design?
Participants are paired together based on characteristics that are relevant to the experiment
Give a strength of the matched pairs design
Order effects and demand characteristics are less of a problem because participants only take part in one condition of the experiment
Give a weakness of the matched pairs design
Matching may be time consuming and expensive, so less economical than other designs
What are participant variables?
Characteristics of the individuals taking part in the study which may affect the outcome of the study
What is random allocation?
Ensure each participant has the same chance of being in one condition as any other
What are order effects?
Confounding variables that arise due to the repetition of tasks
What is counterbalancing?
Half the participants experience the conditions in one order and the other half in the opposite order
What is a laboratory experiment?
Highly controlled environment where the researcher manipulates the IV and records the effect on the DV
Give an advantage of laboratory experiments
Easily replicated due to high levels of control making it reliable
Give a disadvantage of laboratory experiments
Artificial task so low mundane realism
What is a field experiment?
Takes place in a natural setting where the researcher manipulates the IV and records the DV
Give an advantage of field experiments
High mundane realism as environment is natural
Give a disadvantage of field experiments
No control of extraneous variables so cause and effect may be harder to establish
What is a natural experiment?
Researcher takes advantage of a pre-existing IV which would have changed even if the experimenter was not interested in it
Give an advantage of natural experiments
High external validity as they involve the study of real-life issues and problems as they happen
Give a disadvantage of natural experiments
Naturally occurring events may only happen very rarely, so generalisability is limited
What is a quasi experiment?
Have an IV that is based on an existing difference between people e.g. age, which is not manipulated, it simply just exists
Give an advantage of a quasi experiment
High external validity as can control extraneous variables
Give a disadvantage of quasi experiments
Individual differences may play a role
What is internal validity?
The extent to which an experiment can confidently establish a cause and effect relationship between the independent and dependent variables
What is external validity?
The extent to which an experiment can generalise its findings to other situations, such as everyday life
What is random sampling?
All members of the population have an equal chance of being picked
Give a strength of random sampling
Free from researcher bias
Give a weakness of random sampling
Difficult and time-consuming to conduct (list of population may be difficult to obtain)
What is systematic sampling?
Every nth member of the population is selected
Give a strength of systematic sampling
Avoids researcher bias
Give a weakness of systematic sampling
Selected participants may refuse to take part (so begins to looks like a volunteer sample)
What is stratified sampling?
When you divide people into groups (called strata) based on something they have in common and then you randomly pick people from each group
Give a strength of stratified sampling
Produces a representative sample so generalisation possible
Give a weakness of stratified sampling
Identified strata can’t reflect all the ways that people are different so complete representation of the target population not possible
What is opportunity sampling?
Researcher selects anyone who is willing and available
Give a strength of opportunity sampling
Convenient - saves time, effort and money
Give a weakness of opportunity sampling
Researcher bias - controls who they ask to be a part of the study
What is volunteer sampling?
Participants select themselves to be part of the sample
Give a strength of volunteer sampling
Easy - requires minimal input from the researcher and so is less time consuming
Give a weakness of volunteer sampling
Volunteer bias - may attract a certain profile of a person - one who is helpful, keen and curious (affects generalisability)
Give two differences between experiments and correlations
- in experiments researchers control the IV to measure the DV whereas in correlations there is no manipulation of variables
- in experiments you can establish cause and effect whereas in correlations you cannot
PEEL paragraph for a strength of correlations
P - useful for preliminary research
E/E - may suggest ideas for possible future research if variables are strongly related or demonstrate an interesting pattern
L - often used as a starting point before researchers commit to an experiment
PEEL paragraph for a weakness of correlations
P - can’t establish cause and effect
E/E - we don’t know which variable is causing the change and which is the effect
L - causes complications when media reports use correlational data to establish ‘fact’
What are the 3 measures of central tendency?
- mean
- median
- mode
Evaluate mean as a measure of central tendency
+ includes all the values of a data set within the calculation (representative)
- easily distorted by extreme values
Evaluate median as a measure of central tendency
+ not affected by extreme scores
- less representative than the mean as not all scores included in final calculation
Evaluate mode as a measure of central tendency
+ easy to calculate
- does not represent all the data
What are the 2 measures of dispersion?
- range
- standard deviation
Evaluate the use of range as a measure of dispersion
+ easy to calculate
- only considers two most extreme values
Evaluate the use of standard deviation as a measure of dispersion
+ more precise than the range as it uses all values
- can be distorted by extreme values
What does a normal distribution of data look like on a graph?
Symmetrical spread of frequency data that forms a bell-shaped curve (mean, median and mode are all located at highest peak)
What percentage of the population fall between one standard deviation above and below the mean value in a normal distribution graph?
68.26%
What percentage of the population fall between two standard deviations above and below the mean value in a normal distribution graph?
95.44%
What percentage of the population fall between three standard deviations above and below the mean value in a normal distribution graph?
99.73%
What is a positively skewed distribution?
When the long tail of the distribution is on the positive (right) side of the peak and most of the distribution is concentrated on the left
What is a negatively skewed distribution?
When the long tail of the distribution is on the negative (left) side of the peak, and most of the distribution is concentrated on the right
