11) Hypothesis Testing

Question 1

T- test for one mean assumptions

Answer 1

• one sample t-test is valid only if the observations are independent and the distribution of the variable tested is normal
• distribution of the bariability is not the distribition of the sample means given by the central limit theorem
• violation of independence would occur if for example some participants were siblings

Question 2

T-test for two means assumption

Answer 2

• observations are independent
• normal distribution
• have to distinguish if the groups are paired or not
• if unpaired groups, we may or may not assume equal variance

Question 3

Non- parametric tests

Answer 3

• do not make assumnptions about the distribution of the variable
• more flexible but less power

Question 4

Wikcoxon signed rank test

Answer 4

• takes into consideration the magnitude of the difference (unlike sign test)
• sort the differeences and register the rank of each diffference
• calculate sum of ranks and divide for sample size
• average rank of positives