§ 77.01 – What expansion factor should I use for bus services?

(a)    The unit of sampling and measurement you have chosen for your sampling plan determines the expansion factor you should use.

(b)   While you could have chosen any unit of sampling measurement for your sampling plan, it most likely is in one-way bus trips or in round-trip bus trips.

(c)    The following assumes that your sampling plan is based on one-way bus trips.

(d)   For estimating annual total PMT and UPT:

(1)   Use annual total one-way bus trips if your sampling plan is not based on grouping.

(2)   Use annual total one-way bus trips by group if your sampling plan is based on grouping.

(e)    For estimating average daily PMT and UPT by type of service days, use annual total one-way bus trips by type of service days.

§ 77.03 – What sample average should I use for bus services?

(a)    The unit of sampling and measurement you have chosen for your sampling plan determines the sample average you should use. 

(b)   While you could have chosen any unit of sampling measurement for your sampling plan, it most likely is in one-way bus trips or in round-trip bus trips.

(c)    Assuming that your unit of sampling and measurement is in one-way bus trips, Table 77.01 shows the sample averages you should use.

(d)   If your sample happens not to include any one-way bus trips for a particular day type (e.g., Saturday), use the sample average for the entire sample. 

Table 77.01.  Sample Averages for Bus Services

If the service-consumed measure is

and if the measure is

and if your sampling plan is

then you should calculate the following sample average

UPT

for annual total

not based on grouping

UPT/one-way car trip

based on grouping

UPT/one-way car trip by group

for daily average

 

UPT/one-way car trip by type of service days

PMT

for annual total

not based on grouping

PMT/one-way car trip

based on grouping

PMT/one-way car trip by group

for daily average

 

PMT/one-way car trip by type of service days

§ 77.05 – What steps should I follow to calculate sample averages?

(a)    Aggregate the field sample data to the individual service units in your sample after you have identified and corrected any errors in the data. 

(b)   If the unit of sampling and measurement for your sampling plan is one-way bus trips, sum these quantities over individual one-way bus trips in the sample to get sample totals:

(1)   for the entire sample,

(2)   by type of service days,

(3)   by group if your sampling plan is based on service grouping.

(c)    Count the number of one-way bus trips in the sample:

(1)   for the entire sample,

(2)   by type of service days,

(3)   by group if your sampling plan is based on service grouping.

(d)   Divide sample totals by the number of one-way bus trips for the entire sample, by type of service days, or by service group if applicable.

§ 77.07 – How should I determine annual services actually provided as expansion factors?

(a)    You should measure annual services actually provided in the unit of sampling and measurement you have chosen for your sampling plan.

(b)   For estimating annual totals of service-consumed data, you should follow these steps:

(1)   Start with your schedule.

(2)   When the schedule is changed by policy or by emergency conditions, the count from the schedule must be adjusted accordingly.

(3)   You must also include added services such as trippers and other special operations.

(4)   If your sampling plan is based on service grouping, you must also count annual services actually provided for each group.

(c)    For estimating service-consumed data by type of service days, you should also start with your schedule, and exclude scheduled services on atypical days.  Refer to the NTD Reporting Manual for determining what are considered atypical days.