national multiple family submetering and allocation billing program ...

“goose egg,” with no discernible relationship or pattern between the predicted and residual
values.
Adjusted means of the dependent variable can be calculated for subgroups of one of the
independent variables, e.g., average annual water use per unit by billing method, adjusted for the
other variables included in the model. This was done by applying the average values across the
entire sample for each of the independent variables.
Matched pair and pre-post analyses. A dependent t-test is used to compare the mean
difference score between paired measurements, as in a repeated measures (like the pre- and postconversion
analysis) or matched pair design. Like an independent t-test, a p-value is calculated.
SUPPLEMENTAL DATA COLLECTION
Supplemental data were used to provide additional information about each study site,
utility, and various others affected by separate billing. Some of these data were used in the
model estimation process and to qualify end use measurements.
Weather Data
So that the relationship between weather and water use could be explored during the data
analysis and the water use model development, weather data was obtained for each study site.
Average seasonal temperatures and measured precipitation were obtained from a representative
weather station at each participating study site. The data was available over the Internet. If a
study site did not have a weather station (as was the case for Irvine, CA and EBMUD, CA),
geographically similar locations were used as representative stations.
Utility Water and Wastewater Rates
Water and wastewater rates were collected for each participating utility. In addition,
information on rate structures was obtained. Many of these data were available over the Internet
and were supplemented by utility personnel.
Survey of Potential Regulators
The Study included a survey that was sent to potential regulators across the nation to find
out how they are addressing submetering and allocation issues. The survey was sent to:
State safe drinking water administrators
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