Experimental methods Flashcards
Definition of Aim
A general statement of what the researcher intends to investigate, the purpose of the study
Hypothesis
(text book)
A clear, precise, testable statement that states the relationship between the variables to be investigated. Stated at the outset of any study
Hypothesis (notes)
A statement/prediction of what results you expect to find after your experiment
Difference between Aim vs hypothesis
Directional hypothesis
Makes it clear that there are differences between the 2 conditions or two groups of people.
* The MORE sleep a pps has the better their memory performance
Words used in directional hypothesis
Higher/lower, faster/slower, more/less
Examples of Directional
People who drink … become MORE talkative than people who don’t
Students will remember MORE words in the morning THAN the afternoon
Non-directional hypothesis
Does not state the direction of the difference or relationship
Examples of ND
People who drink … differ in terms of talkativeness compared with people who don’t drink (same thing)
There WILL BE A DIFFERENCE between numbers of words recalled in the morning or afternoon
Directional vs ND: When to use which?
- Directional - used when there already has been a range of research carried out before
- ND - no previous research has been done
Difference between Directional vs Non-directional
- Directional - specifically states which will be higher and lower
- ND - just states there is a difference
Which hypothesis to pick?
(ND)
ND (two tailed test) - researcher doubling chances of getting a significant of results.
Usually used if no previous research into your area/previous findings are contradictory
Which hypothesis to pick
(Directional)
Directional (one tailed test) - researcher is ‘sticking their neck out’ + making a more specific prediction.
Usually used if previous research suggests a specific outcome, also used if psychologist is trying to disprove/challenge previous research
Null hypothesis
A statement of no difference or no relationship
Example of null hypothesis
There will be NO DIFFERENCE in the amount of words they recall and when they listen to music
Alternative hypothesis
The alternative to the null (the prediction we believe to be true)
Experimental hypothesis
A statement that predicts the difference you expect to find in the DV when the IV is manipulated/controlled
Experimental method
Theory proposed –> Hypothesis/prediction based on theory –> variable manipulated (IV) –> performance measured (DV) –> theory supported or refuted according to the outcome
Levels of the IV
Two levels: the control and the experimental condition
Lvls of IV example
Students who complete a memory test in the MORNING (lvl 1 of IV) will recall more (directional) words (DV operationalized) than students who complete a memory test in the afternoon (lvl 2 of IV)
Operationalization
Clearly defining variables in terms of how they can be measured. A more detailed version of the variables. Making something clear/unambigious
Example of an operationalized hypothesis
After drinking 300ml of … , participants say more words in the next five minutes than pps who drink 300ml of water
VS
not operationalized - the group that drinks an energy drink will be chattier than the group that drinks water
