Sampling Techniques and Methodology

IFTA/IRP Audit WorkshopFt. Lauderdale, FL

February 2014

Presented by: Anthony Madsen - Washington

Bob Schwab – MissouriDawn Lietz - Nevada

Company Overview

Name: Snow Bird Delivery Services DBA: Coast to Coast Express

Motto: “Leave the driving to us.”

Company Size: 150 UnitsDemographics: All Continental US and DCAverage Reported:

Distance per Unit: 40,079Fuel per Unit: 6,956

0 – 2%

2.1 – 3.5%

3.6 – 5%

Hitting the Mark - % of Error

Sampling Techniques & Methodology – MilesStatisticalJudgmental/random ie.

◦choose every nth unit to arrive at your determined size based on the population

◦choosing units ending in the nth to arrive at your determined size based on the population

Random number generator

Sampling Techniques & Methodology – FuelStatisticalJudgmental/random ie.

◦select fuel for sample units◦choose nth ticket by jurisdiction

Sampling Concepts:

What method is best?

What items should be considered when sampling? Should it be completely random?

Considerations:

Change in operations

Multiple locations – same system?

Fleet makeup – different unit types

Considerations Cont’d:

Do you need to sample every jurisdiction?

Will you get accurate results if you include a jurisdiction with significant operations, but for only one or two trips?

Audit Scope

Audit Period: 1/1/2012 – 12/31/2012Sample Period: 01/01/2012 – 03/31/2012 (12/01)Sample Size: 15 Units (10%)

Audit Period:Total Reported Miles: 24,047,545Total Reported Gallons: 4,174,021

Sample Period:Total Reported Miles: 4,628,264Total Reported Gallons: 807,462

Audit Sample of 15 Units

Pulled every 15th vehicle

Reported Total Sample Units:Total Reported Miles: 396,058 Total Reported Gallons: 70,604

Actual of Total Sample Units Audited:Total Audited Miles: 406,616 (2.67%)Total Audited Gallons: 68,054 (-3.61%)

Audit Sample of 15 Units

In class random number generator:

Reported Total Sample Units:

Actual of Total Sample Units Audited:

Drilling further….Let’s look at the effect to individual jurisdictions.

0 – 2%

2.1 – 3.5%

3.6 – 5%

Hitting the Mark - % of Error

How does a sample affect an audit? Summarizing:

Applying results of a sample should not be done blindly!

Without careful examination, inconsistent or unreasonable results could occur!

Adjust the results during field work instead of during appeal!

Thank YOU for your participation