probability and significance Flashcards
how do you work out the P (probability) value?
number of particular outcomes / number of possible outcomes
what is the usual P value?
0.05
it is an arbitrary P value
what are the null and alternate hypotheses?
•null- there will be no relationship between the two variables
•alternate- there will be a relationship between the two variables
what is a significant result?
•if the result is under 0.05 (or your chosen P value)
•this increases the chance that your result was due to the independent variable and not extraneous factors
what might it mean if your result is above 0.05?
that the result you got would have happened with or without manipulating the independent variable
it increases the likelihood that it was down to chance
why might you make the P value more lenient?
•if it’s the first time the experiment has been completed
•if it’s a pilot study
why might you make the P value more stringent? (eg 0.03)
•if you’re repeating the experiment (as it increases the reliability of conclusions)
•if it’s socially sensitive research and has significant implications (you need to be sure of the relationship between the two variables)
what is a type 1 error?
when you incorrectly accept the alternate and reject the null
what causes a type 1 error?
when the P value is too lenient
what is a type 2 error?
when we incorrectly accept the null and reject the alternate
why does a type 2 error occur?
because the P value is too stringent
a psychologist used a P value of 0.03, why are they confident they haven’t made a type 1 error?
•a type 1 error is when you incorrectly accept the alternate hypothesis and reject the null
•this occurs when the P value is too lenient
•0.03 is a stringent P value and therefore it is unlikely it will result in a type 1 error
