Week 9: Limitations NHST

Question 1

absolute effect size

Answer 1

lab group mean - control group mean

Question 2

relative effect size / cohen’s d head

Answer 2

(lab mean - control mean) / pop sd

Question 3

rule of thumb of cohen’s d head

Answer 3

• 0.2, small effect
• 0.5, medium effect
• 0.8, large effect

Question 4

p-hacking

Answer 4

• continue/stop gathering data depending on p <> 0.05
• doing a 1-tailed test after 2-tailed was not significant
• trying different test and selecting test that gives p < 0.05
• remove ‘outliers’ to get p < 0.05
• only report significant tests, not reporting non-significant test

Question 5

HARKing

Answer 5

• unexpected significant result after data collection: pretend it was hypothesized