Statistics 1 Revision Notes - Mr Barton Maths

Question 2
Give two other reasons why these data are negatively skewed.
Answer
For negative skew; Mean < median < mode: 49⋅4 < 52 < 56
Q 3 – Q 2 < Q 2 – Q 1: 8 < 17
Question 3
Describe the skewness of the distribution. Give a reason for your answer.
Answer
No skew or slight negative skew.
0.22 = Q 3 − Q 2 ≈ Q 2 − Q 1 = 0.23 or 0.22 = Q 3 − Q 2 < Q 2 − Q 1 = 0.23
or mean (3.23) ≈ median (3.25), or mean (3.23) < median (3.25)
Correlation
Question 1
Give an interpretation of your PMCC (–0⋅976)
Answer
As height increases, temperature decreases (must be in context).
Question 2
Give an interpretation of this value, PMCC = –0⋅862.
Answer
As sales at one petrol station increases, sales at the other decrease (must be in context).
Question 3
Give an interpretation of your correlation coefficient, 0⋅874.
Answer
Taller people tend to be more confident (must be in context).
14/04/2013 Statistics 1 SDB 45