probability and significance Flashcards
how is the probability sign shown?
-p value
key features of probability
-found always between 0 and 1
-statistical tests to work out how probable it is that something might occur
-research studied have experimental or null hypothesis to be tested
-allows to decide wether ur rejecting or accpeting hypothesis(depend on result)
what does gaining a significant result mean?
-low probability that chance factors were responsible for the result
what does a result being closer to 1 mean?
-more likely results are due to chance
what does P=1 mean
-100% certain that something will happen by chance
what does your p value being closer to 0 mean
-the less likely its due to chance
-more likely to accpet our experimental hypothesis
-reject null hypothesis
what does a alternative hypothesis look like?
-‘after drinking 300ml of speedupp particpants say more words in the next 5 mins than participants who drink 300ml of water’
-opposite to null
what is a null hypothesis and example
-states theres no difference
-‘theres no difference in the number of words spoken in 5 mins between participants who drink 300 ml of speedupp and participants who drink 300ml of water’
what is the 5% significance level?
-is p≤0.05
-equal to or less than 5%
-95% not due to chance
and acc due to IV
-type 1 and type 2 error can be balanced this way
why do some psychologists choose 1%
-choose to be more’strigent’
-for exmaple for medical testing
-have to be sure its effective or safe
what is a type 1 error?
(false positive)
-reject null hypothesis when we shouldnt
-significance level is too high
-think theres phenomenom but there isnt
what is type 2 error?
-accept null hypothesis when we shouldnt
-significance level too low
-may miss the phenomena
key features of critical value/ observed values
-when we carry out a test we get a result = caluclated value /observed value
-need to comapre to critical claue in table
-in some tests calculated value msut be equal to greater than critical value
-and for others calculated value must be equal to or less than the ciritcal value
-FOLLOW THE RULE OF ‘R’
how do you which critical value to use?
1.one tailed(directional) or two tailed hypothesis(non directional)
2.no of particpants in the study -appears as the N value in the table
(some tests use degree of freedom)
3.level of significance
what is the rule of R?
-some statisitical tests require the calculated value to be equal to or more than the critical value for significance
-for other tests the calculated value must be equal or less than critical value
-stats tests with ‘R’ in their name are those where calculated value must be equal to or more than critical value.
