aims and hypothesis

• aims are developed from theories. they are general statements that describe the purpose of an investigation. if we were right an aim it would look something like 'to investigate whether drinking energy drinks (IV) makes people more talkative (DV)
• a hypothesis is a statement that is made at the start of a study and clearly states the relationship between variables as stated by the theory. it may look something like 'drinking redbull (IV) causes people to become more talkative (DV). hypothesis can be directional or non directional. in a directional hypothesis the researcher makes clear the difference that will be anticipated between the two conditions or two groups of people (higher, lower etc). a non directional hypothesis states that there is a difference between conditions but the nature of the difference is not specified
• psychologists tend to use directional hypothesis when research has previously been conducted which suggests a particular outcome. whereas a non directional hypothesis will be used when research has not previously been conducted
• in an experiment, a researcher changes the independant variable and records the effect of this change on the dependant variable. all other variables that affect the DV should remain constant in a properly controlled experiment. this is so the researcher can be confindent that the cause of the effect on the DV was the IV alone
• to test the effect of the IV, different experimental conditions must be considered. there are two levels of the IV: the control condition and the experimental condition.
• it is important to make sure each of the variables are operationalised so they can be easily measured