Scientific Processes- (Aims, Hypotheses, Sampling, Control,Experimental Design) Flashcards
What is an aim?
A general statement of what the researcher intends to investigate, to be clear about the purpose of the study .E.g. To investigate the effect….
What an aim of a correlational study?
should reflect that correrlational studies investigate possible relationships, rather than cause and effect .e.g. to investigate the relation ship between…..
What is a hypothesis?
precise, testable statement made at the beginning of an investigation about what the researcher expects happens
What is the difference between an aim and a hypothesis?
Aim is a general statement of the purpose of the study, hypothesis is a precise and testable statement
what are the two main hypothesises
Alternative hypothesis and null hypothesis
What an alternative hypothesis?
-Used in any study, regardless of the research method
what can the alternative hypothesis be called?
An experimental hypothesis or a correlational hypothesis
what is an experimental hypothesis?
when an experimental method is used, and must include the independent variable and dependent variable
What is a correlational hypothesis?
When a correlational method is used and so must include the covariables
What two things can an alternative hypothesis be?
Directional or non-directional
What is the directional hypothesis?
States of direction in which the results go,
states which set of scores will be better/faster/positively or negatively correlated.
when is the directional hypothesis used?
When research suggests a direction
What is an example of a directional hypothesis
Participants remember significantly more words when they study in short base of 10 minutes, then when studying for longer sessions of one hour
What is a nondirectional hypothesis?
States that there will be a difference, but does not state the expected direction of the outcome
When is a non-directional hypothesis used?
When there has been no, previous research or previous research has found contradictory results
What is an example of a non-directional hypothesis?
there is a significant difference in the number of words recalled by participants who study in short bursts of 10 minutes to those who study for long sessions of an hour
what is a null hypothesis?
States there’s no difference, and the results are due to chance
Was an example of a null hypothesis
There is no significant difference in the number of words record by participants who study in short bursts of 10 minutes, compared to those who study for longer sessions of one hour
What tense is a hypothesis written in?
present tense because they are statements tested during a study
What is an IV?
variable manipulated by experimenter or altered by situation/ characteristic of participants, to observe the effects in the DV
what do changes to the independent variable create?
The conditions of the experiment
What is the DV?
The variable that is measured by the experimenter
what is an extraneous variable?
any variable other than the IV that might affect the dependent variable e.g. level of alertness
what are the four extraneous variables?
-Participant variables
-Situational variables
-Demand characteristics
-Investigator effects
Why should extraneous variables be controlled?
So they didn’t become confounding
What is a cofounding variable?
Any variable other than the independent variable that does affect the dependent variable
What is the best extraneous variable to ever look for?
The task
what is the meaning of operationalisation of variables?
Needs defining variables clearly, so they can be specifically tested and measured accurately
What does designs mean in experimental designs?
How are your participants allocated to conditions in your experiment?
What is repeated measures design?
The same participants are used in all conditions of the independent variable
What are advantages of repeated measures?
-individual differences eliminated, so any difference between their performance in each level of the IV should be the experimenters manipulation
-Fewer participants required
What are disadvantages of repeated measures design?
-order effects.eg. practice, boredom- (although can be evenly distributed across conditions by counter balancing-ABBA)
-DC- all participants take part in all conditions
-Not possible to use the same material in each condition
what is independent groups design?
Participants in separate groups- Each group does one level of the IV
What are the advantages of independent groups design?
-No order effects- participants only involved in one condition
Less opportunity to become aware of aim (reducing demand characteristics
-same material can be used in all conditions because participants only do one condition of the experiment
What are disadvantages of independent groups design?
participant variables are introduced (differences between conditions may be caused by different people rather than the IV)
-No Participants required
what is matched pairs design?
Pairs of participants are closely matched on a relevant characteristic- eg age
each spring is randomly allocated to one conditions or the other
What are advantages of matched pairs design?
-avoid order effects
-Avoids DC
-Reduces ID’s (can’t eliminate)
-Same material can be used in both conditions
What are disadvantages of matched pairs design?
-difficult to match everything about participants
-Very time-consuming, and requires more participants
What is random allocation?
-allocating participants to experimental groups in an unbiased way, so they have an equal chance of being selected to take part in each condition
-this is to distribute participant characteristics across the conditions to avoid extraneous variables and improves internal validity
-Used to address problem of participant variables in independent design
What is counterbalancing?
-used to control the impact of order effects in repeated measures design and improve internal validity
-Involves making sure each condition comes first or second in equal amounts
-in order effects are distributed evenly across all conditions
-Does not reduce OE has all participants still take part in all conditions therefore they are still present, but their effect is balanced across the conditions
what is randomisation?
-use of chance wherever possible when designing materials and deciding the order of conditions
-This is to avoid research bias influencing the design of the study-it is an attempt to control investigator effect and improve internal validity
What is standardisation?
-ensuring all participants have exactly the same environment, information and experience, so individual experience does not confound the result thus improving internal validity
what do standardised procedures ensure?
all participants are tested under the same conditions to enable to deal with experiment, bias, and facilitate replication to ensure findings can be checked for reliability.
what should standardised procedures include?
set of standardised instructions that are given in the same way to all participants to deal with investigator effects
what are the four ways to control experiments?
Random allocation
Counter balancing
randomisation
Standardisation
What is random sampling?
-where every member of the population has an equal chance of being selected
(names in hat)
what are the strengths of random sampling?
less biased- all members of target population have an equal chance of selection
What are the limitations of random sampling and systematic sampling?
-May not be representative of the population-possible by chance, the randomly selected sample is biased anyway (too many males)
-Relies on all target population, being able to take part of selected
-Need to have access to all names of target population
what is systematic sampling?
This method involves selecting every participant from the list of available participants (every fifth person from a list of 50 participants)
What are the strengths of systematic sampling?
The only researcher involvement is deciding the sample size, it reduces investigator bias
what is stratified sampling?
Sub groups/strata within a population are identified. participants are obtained from each strata in proportion to the occurrence in population.
-Selection from the strata is done, using a random technique
what are the strengths of stratified sampling?
-by guaranteeing all the key characteristics of the population are in the sample, it avoids investigator bias afterwards, but it can also be representative and be generalised.
what are the disadvantages of stratified sampling?
-If all key features a population are not identified, then the sample may not be representative(limiting generalisability)
-very time-consuming to identify sub groups and then select participants randomly
-Need to know names of all target population
What is opportunity sampling?
-Most common method
-approach anyone in the immediate area who happens to be available to ask to participate
What are the strengths of opportunity sampling?
easiest method as you use the first participants that you find (takes less time to locate your sample than other methods)
what are the disadvantages of opportunity sampling?
-unlikely to be representative of the target population ad the sample is taken from a small part of the target population
-researcher may consciously or unconsciously show bias in the sample selection, thus limiting generalisability
what is volunteer (self-selected) sampling?
-advertisements are used to attract participants (they volunteer themselves)
-Usually requires an incentive (payment/prize)
What are strengths of volunteer sampling?
an easy method to use (less initial work involved than in random sampling)
What are the disadvantages of volunteer sampling?
-sample bias is likely (only certain) types of people are likely to volunteer-they are atypical respondents with the characteristics, not necessarily common of the population e.g. highly motivated.)
This limits generalisability
How do you improve the reliability of experiments?
-more than one measurement from each participant and take a mean score (reduced impact of any anomalous score)
-pilot studies- used to check the proposed method measurements works properly and that participants can use any apparatus successfully
How can you improve the external validity of experiments? (ecological validity)
Ecological validity can be improved by conducting the experiment in a more naturalist, real life setting e.g. field experiment
How can you improve the external validity of experiments (population validity)
-can be improved by taking larger, more varied samples, for example including a wider age group or geographical area
