research methods

• aim = a general statement of what the researcher intends to investigate, the purpose of the study
• hypothesis = a clear, precise statement thar states the relationship between the two variables being investigated. stated before any study takes place. a prediction of what the researcher thinks will happen
• directional hypothesis = states the direction of the difference or relationship
• non-directional hypothesis = does not state the direction of difference
• variables = anything that can change or vary within an investigation. generally used to determine if changes in one thing results in changes to another
• independent variable(IV) = the variable that is manipulated or changed by the researcher so the effect on the DV can be measured.
• dependent variable(DV) = the variable that is measured by the researcher. any effect on the DV should be caused by a change in the IV
• operationalisation = clearly defining variables in terms of how they can be measured
• extraneous variable = any variable other than the IV that may have an effect on the DV if it is not controlled. they not vary systematically with the IV
• cofounding variable = any variable other than the IV that may affect they DV such as personality, so we can't be sure of the true sources of changes to the DV. cofounding variables vary systematically with the IV
• demand characteristics = any cue from the researcher that may be interpreted by participants as revealing the purpose of the investigation. this may lead to participants changing their behaviour within the research situation
• investigator effects = any effect of the investigator's behaviour (conscious or unconscious) on the research outcome (the DV). this may include everything from the design of the study to the selection or interaction with participants during the research process.
• randomisation = the use of chance in order to control for the effects of bias when designing materials and deciding the order of conditions.
• standardisation = using the exact same formalised procedures and instructions for all participants in the study
• independent group design = two separate groups of participants experience two different conditions of the experiment. e.g. group A drink an energy drink (experimental condition) and group B drink water (control condition). the performance of the two groups would be compared.
• repeated measures = all participants take part on all the experimental conditions. then all sets of data would be compared to see if there was a difference.
• matched pairs = pairs of participants are first matched on some variables e.g. IQ levels, that may effect the DV outcome. then one member of the pair is assigned to condition A and the other to condition B. this is an attempt to try and control participants variables.
• random allocation = an attempt to control for participant variables in independent group design which ensures that each participant has the same chance of being on one condition as any other.
• counterbalancing = an attempt to control for the effects of order in a repeated measures design. half the participants experience the conditions in one order and the other half in the opposite order
• independent group design- A03

  + order effects are not a problem and the participants are less likely to guess the aim of the experiment

  -the participants who occupy different groups are not the same, if the researcher finds mean difference between the two groups this may be due to individual differences which can be sorted by using random allocation

  -less economical as a participant only contributes a single result, they would need to produce two results to make it more equivalent
• repeated measures-A03

  +participant variables are controlled and less participants are needed

  -each participant has to do at least two tasks and the order of these may be significant and to deal with this researchers use counterbalancing

  -order effects also arise because repeating two tasks may create boredom or tiredness meaning deterioration in the second task no matter the order

  -it is more likely participants may guess the aim of the study for this reason demand characteristics tend to arise more
• matched pairs-A03

  +participants only take place in one condition so order effects and demand characteristics are less of a problem

  -participants can never be matched exactly so there will still be some differences that may affect the DV

  -can be time consuming and expensive so is less economical
• labatory experiment = conducted in highly controlled environments. where the researcher manipulates the IV and records the effect on the DV. it isn't always in a lab but a setting where variables are well controlled
• field experiment = an experiment that takes place in a natural setting within which the researcher manipulates the IV and records effects on the DV
• natural experiment = when the researcher takes advantage of the pre-existing independent variable. the variable would not have been changed even if the experimenter was not there, the researcher records the effects on the DV.
• quasi-experiment = has an IV based on an existing difference between people e.g. gender. no one has manipulated this variable it just exists.
• lab experiment-A03

  + high control over extraneous variables therefore we can be more certain about the cause and effect (high internal validity)

  +replication is less likely because of high level of control meaning no new extraneous variables are introduced

  -may lack generalisability as lab environment is more artificial so behaviour can't be observed beyond research setting (low external validity)

  -low mudane realism as tasks may be artificial

  -demand characteristics as participants are aware they're being studied
• field experiment-A03

  +have higher mundane realism because environment is more natural

  +may produce behaviour more valid and authentic because participants may be unaware of the study (high external validity)

  -loss of control and effect so can be more difficult to establish and precise replication is often not possible

  -ethical issues, participants aren't aware so they can't give consent to be studied so may invade privacy
• natural experiment-A03

  +often have high external validity as they involve the study of real life issues such as effect on stress levels

  +provide opportunities for studies that might not be undertaken for practical or ethical issues e.g. Romanian orphan study

  -a natural event occurring is very rare reducing opportunities for research and generalising to other findings

  -participants may not be randomly allocated to conditions meaning researcher may be less sure whether the IV affected the DV
• quasi-experiment-A03

  +often carried out in controlled conditions

  -can't be randomly allocated and therefore may be cofounding variables
• random sampling = where all members of the target population have an equal chance of being selected. e.g. giving people in a list a number and using a number generator or pulling out a hat to choose
• systematic sampling = every nth member of the target population is selected, e.g. every 3rd person on a register. a sampling system is nominated and this interval may be determined randomly to reduce bias. the researcher then works through the sampling frame until the sample is complete
• stratified sampling = the composition of the sample reflects the proportions of people in certain sub-groups. within the target or wider population. the researcher first identifies the different strata that makes up the population then the proportions needed for the sample to be representative are worked out. finally, the participants that make up each spectrum are selected using random sampling
• opportunity sampling = decide to select anyone who is willing and available. the researcher simply takes the chance to ask whoever is around at the time of the study e.g. on the street
• volunteer sampling = participant selecting themselves to be a part of the sample also known as self-selection. to select volunteer sample a researcher may place an advert in a newspaper or in a common room of people