Inferential stats Flashcards
What is inferential stats?
Probability estimates
Conditional probability calculation is A and B are independent
p(A) x p(B)
Conditional probability calculation if not independent
p(a) x p(BIA)
Conditional probability calculation is not mutually exclusive
p (AorB) = p(A) + p(B) - p(AandB)
Gamblers fallacy
It’s happening a lot now so won’t happen in future
Law of small numbers
Exagerated confidence in small numbers e.g. winning the lottery
COnjunction of the inverse
probabilty of A given B does not equal probability of B given A
95% of population fits in what z score value
+/- 1.96
Calculation of z score
x - mean / SD
Calculation for statistical model
outcome = (model) + error
What alters a model?
Design, type of data and hypothesis
Whats the simpliest model
Mean
Sum of sqaured error =
total deviation of scores from the mean (good accuracy measure)
What are degrees of freedom?
Number of variables free to vary
What is good about standard deviation?
Can be compared because it’s standardised
What improves with more ppts?
Sampling distribution and frequency distribution approach normality
How can you measure how closely a sample compares to the mean?
Standard error of the mean or SD of sampling distribution
Central limit theroem
As sample size increases normal distribution will be reached (above sample size of 30)
If a sample size is smaller than 30 what distribution is used?
t-distribution
