Inconsistent UCC usage in Consumer Expenditure Survey

Question

This question perhaps does not belong here. If you do know where it belongs, please let me know and I will delete the question.

Data: Consumer Expenditure Survey from the BLS (PUMD)

Files used: MTBI (expenditure by UCC codes) and FMLI (expenditure per category)

Goals: 1) Make a time series of FMLI data. 2) Fine tune some FMLI variables by dropping some UCC from the MTBI files and reconstructing them.

Problem: The same variable is sometimes constructed from different UCC.

For example: The variable MAINRPPQ (Maintenance and repairs last quarter) in 2012 and 2013 CE files.

For 2012 the UCC used are:
"470220 COOLANT/ADDITIVES/BRK/TRNS FLD"
"480110 TIRES PURCHASED/REPLACED/INSTALL"
"480212 VEHICLE PRODUCTS & SERVICES"
"480213 PARTS/EQUIP/ACCESSORIES"
"480214 VEHICLE AUDIO EQUIPMENT"
"480215 VEHICLE VIDEO EQUIPMENT"
"490110 BODY WORK AND PAINTING"
"490211 CLUTCH, TRANSMISSION REPAIR"
"490212 DRIVE SHAFT AND REAR-END REPAIR"
"490221 BRAKE WORK"
"490231 REPAIR TO STEERING OR FRONT END"
"490232 REPAIR TO ENGINE COOLING SYSTEM"

but for 2013 the UCC are:
"470220 COOLANT/ADDITIVES/BRK/TRNS FLD"
"480110 TIRES PURCHASED/REPLACED/INSTALL"
"480212 VEHICLE PRODUCTS & SERVICES "
"480213 PARTS/EQUIP/ACCESSORIES"
"480215 VEHICLE VIDEO EQUIPMENT"
"480216 VEHICLE CLEAN SRVCS INCL CARWASH"
"490110 BODY WORK AND PAINTING"
"490232 REPAIR TO ENGINE COOLING SYSTEM"
"490300 VEHICLE OR ENGINE REPAIRS"
"490311 MOTOR TUNE-UP"
"490312 LUBE, OIL CHANGE AND OIL FILTERS"
"490313 FRNT END ALIGN, WHEEL BAL/ROTAT"
"490314 SHOCK ABSORBER REPLACEMENT"
"490318 TIRE REPAIR AND OTH REPAIR WORK"
"490501 VEHICLE ACCESSORIES INCL. LABOR"
"490900 AUTO REPAIR SERVICE POLICY"

There are five issues:

1. UCC that are in the 2012 variable but are not in the 2013 variable:
   "480214 VEHICLE AUDIO EQUIPMENT"
   "490211 CLUTCH, TRANSMISSION REPAIR"
   "490212 DRIVE SHAFT AND REAR-END REPAIR"
   "490221 BRAKE WORK"
   "490231 REPAIR TO STEERING OR FRONT END"

2. UUC that are in the 2013 varaible but are not in the 2012 variable:
   "480216 VEHICLE CLEAN SRVCS INCL CARWASH"
   "490300 VEHICLE OR ENGINE REPAIRS"
   "490311 MOTOR TUNE-UP"
   "490312 LUBE, OIL CHANGE AND OIL FILTERS"
   "490313 FRNT END ALIGN, WHEEL BAL/ROTAT"
   "490314 SHOCK ABSORBER REPLACEMENT"
   "490318 TIRE REPAIR AND OTH REPAIR WORK"
   "490501 VEHICLE ACCESSORIES INCL. LABOR"
   "490900 AUTO REPAIR SERVICE POLICY"

3. The UCC that are in 2012 but not in 2013 variable still exist in the 2013 UCC text file and MTBI files. So, why were they dropped? From the description of the new UCC in 2013, I could not find the reason.

4. Some of the UCC that exist in 2013 but not in 2012 were measured in 2012 but some were not.

5. I could not find documentation of what is going on without manually going through everything.

My questions are:

1. Does proper documentation of UCC changes in the CE exist? If a code exists both in 2012 and 2013, but is not used in 2013, what is the reason? Please note that in 2013, "Brake Work" was dropped...
2. What should be my strategy for time series variables?

Thank you.

Answer 1

Documentation:

2012
http://www.bls.gov/cex/2012/csxintvwdata.pdf
2013
http://www.bls.gov/cex/2013/csxintvwdata.pdf

Search for "470220" in both and you'll see UCC defined, and 2012 is clearly different from 2013.

I'll bet the why are they different is buried in the documentation too, although I'm certainly to lazy to pick through it.
http://www.bls.gov/cex/csxmicrodoc.htm