Probability, significance and statistical tests Flashcards
What is a calculated value?
A number produced by working out a statistical test
What does the null hypothesis predict?
That there’ll be no effect between variables
What does the alternative/ experimental hypothesis predict?
That one variable will effect the other
What does ‘P=’ represent?
The percentage that the results are due to chance
What percentage must results be in order for them to be significant?
Less than 0.05
P<0.05
Which hypothesis is accepted and which is rejected if results of a study are significant?
Accept experimental
Reject null
Which hypothesis is accepted and which is rejected if results of a study are not significant?
Accept null
Reject experimental
What is a type I error?
When experimental is accepted and null rejected even though the results are due to chance
(false positive)
What is a type II error?
When null is accepted and experimental rejected even though the results weren’t due to chance
(false negative)
What is a critical value?
A number that tells us whether or not we can reject the null hypothesis
What is nominal level data?
Frequency/ count data consisting of the number of pps falling into categories
(CATEGORIES)
What is ordinal level data?
Data presented in rank order
(RANK)
What is interval level data?
Data measured in fixed units with equal distance between points on the scale
(EQUAL INTERVALS)
Phrase to help remember statistical tests
(Nom Ord Int)
Space Weather Really
Contains Many Ufos
Chasing Small Pigs
(first row is related - RMD/MPD)
(second row is unrelated - IGD)
(third row is correlation)
Which statistical tests are for related data?
Sign test (ordinal)
Wilcoxon (nominal)
Related t-test (interval)
