2) Does correlation equal causation? Does the strength of correlation depend on the direction? What is the meaning of a zero correlation? Explain your answers.
3)What does a 'statistically significant' result mean? How do we know whether a relationship between two variables is caused by something other than mere random chance?
4)What does a small p-value, lower than the level of significance indicate? Explain using specific examples
5) Does the strength of correlation depend on the direction? What is the meaning of a zero correlation? Explain your answers.
6) What is the purpose of using regression analysis? How may it be used to formulate strategies?
7) A private mail delivery service has a policy of guaranteeing delivery by 11:00 A.M. on the morning after a package is picked up. Suppose that the management of the service wishes to check the delivery performance in a particular area over a 2-week time period based on a five-day workweek. The total number of packages delivered daily and the number of packages that were not delivered by 11:00 A.M are shown below:
Day
Packages Delivered
Packages not Arriving before 11:00 A.M.
1
136
4
2
153
6
3
127
2
4
157
7
5
144
5
6
122
5
7
154
6
8
132
3
9
160
8
10
142
7
Based on the above data, can we conclude that the postal delivery process is out of control? [hint: if possible, create control limits and a p-chart for the above data].