The TPOPS will have a quarterly rotating panel design.
Accompanying the transition from CPOPS to TPOPS is the introduction of a completely revised set of POPS categories, redefined to reflect the 1998 item classification structure.
Once the TPOPS is fully operational, every sampling unit will be assigned one of the 16 POPS questionnaires for interviewing each quarter.
The CATI TPOPS has numerous advantages over the personal-visit CPOPS.
Instead of rotating all commodities and services in 20 percent of all geographic sampling areas each year, under the TPOPS a portion of all commodities and services will be rotated in every geographic sampling area every year.
Under the TPOPS, POPS category rotation is more flexible.
The TPOPS sampling frame will be constructed from a random list of telephone numbers; by contrast, the CPOPS sampling frame was constructed from the 100-percent detailed address file from the decennial census.
Data capture under the TPOPS will be significantly more efficient than under the CPOPS, in which responses are first transcribed onto questionnaires and then keyed into a computer by data processors months after the interview occurred.
However, for every consumer unit interviewed in the CPOPS, the Bureau must interview roughly 3.4 consumer units in the TPOPS in order to administer all POPS categories.
The total number of initiations required per sampling unit per year will increase from 0.2 to 4 under the TPOPS. This will balance the work load of the average BUS field representative from month to month.