1. Short Course in Statistics Variation 2
Rick White
Department of Statistics
UBC
Lecture 5

2. The story so far …
Recall the scenario: you are in a sales team selling widgets for Stats Inc. in your region.
Sales figures for your first six months have been reported and compared with the other sales teams.
One team was ahead, one lagging sadly behind …

3. Your next six months …
Simulate your team’s next six month sales figures using Excel as before.
Recall for Distribution select Normal, with mean 16000, standard deviation 5000.
For Seed enter the birthday of the mother of the second youngest member of your team, in the form ddmm.
Report your mean monthly sales for the year.

4. Your next two years …
We will not use Excel for the next 25 months. We use the on-line applet at
st/index.html
Click Begin. Our Normal distribution is pictured, in thousand $s.
Select N=25 in the third set of buttons (for the Distribution of means).
Your next 25 sales figures will be generated by clicking Animated. Work hard!
Report your team’s mean to your line manager.

5. What do you notice?
How did the 25-month means vary compared to the monthly sales figures for the first year? Which appears most variable?
How did the 25-month means vary compared to the six-month averages from lecture 4?
Is this what you would expect?

6. Not all are equal …
Now one team has an edge, sampling sales from a Normal distribution with mean $18k.
Create six more monthly sales figures. For Random Seed enter the birthday of the father of the oldest member of your team, in the form ddmm.
For Output options, check New Worksheet, and click OK.
Report your mean monthly sales.

7. Complete the year …
Create six more monthly sales figures. For Random Seed enter the birthday of the father of the second oldest member of your team, in the form ddmm.
Report your mean monthly sales for the year.
What do you notice? What would you expect if there were twenty other teams all simulating sales from a Normal distribution with mean $16k and s.d. $5k?