§ 63.09 – How do I develop the list of all service units for using a table of random numbers?

(a)    Suppose that:

(1)   you have chosen weekly sampling for your vanpool service,

(2)   your sampling plan requires 2 vanpool-days per week,

(3)   you want to select a random sample for next week, and

(4)   you have 101 vanpools and each of them is expected to operate every day next week.

(b)   One way to develop the list would be to assign a serial number of four-digits to each vanpool-day for all 707 combinations of vanpools and service days.  The first digit would represent the day of week with 1 for Monday and 7 for Sunday.  The other three digits would represent vanpool numbers ranging from 001 through 101.

(c)    The vanpool numbers may differ from what you use for your internal purposes.  Make sure that you have a one-to-one list between the internal vanpool numbers and the new serial numbers if they differ.

(d)   The serial numbers on a given day must be consecutive without any gaps.

(e)    Write down just the first and the last for each day of week so that you will know the range of numbers.  For example, the range for Monday is 1001-1101.

(f)    You should summarize these serial numbers in a summary table as in Table 63.03.

Table 63.03.  Example of a Summary Table of Serial Numbers

Day of Week

Range of Serial Numbers

1 (Monday)

1001-1101

2

2001-2101

3

3001-3101

4

4001-4101

5

5001-5101

6

6001-6101

7

7001-7101