standard error and confidence intervals Flashcards
what is standard error
the standard deviation of the distribution of sample meaans measures the spread oif popualtion mean
where does 95% of a sample lies
within the SD
how can uf-us be small but the t test ratio is large
due to small SE
what are the three assumptions of a t test (unpaired)
- the two samples are independant
- the two samples follow normal distribution
- the population SDs are equal
what does an unpaired t etst assume
that the population is normal
what does a paired test assume
that their are differnces in normlaiity
how much of the popualtion lies between the two SDs
95%
what is the reaonsable range to see if the mean is within the 95%
(-2SE,2SE)
what are the 3 steps for setting up a t test
- make a null hypothesis
- set the signifcance level
- calcaulting the chance of falling between -2SE, 2SE
what is the short hand t test stat
ms-mf/se
what would using an unpaired t test do when they are meant to be paired
increase SE and P value and get a smaller T test statistic
if there is a significant assocaition from a t test where would you expect to see mf-ms/se
outside of -1.96 and 1.96
how are vairiables treated in regression analysis
not equally
how are variables treated in correltaion analysis
equally
are residual considered normal
yes
