### Changes to the US Renewable Fuel Standard Program: **Petition for an Aggregate Compliance Approach for Canadian Crops and Crop Residues**  **Procedure and Rationale**  **for Trend Analys** **i s**  **used in Data Comparability, Analysis and Justification** 

**Estimates for Pastureland**  The annual surveys of field crops and hays (as mentioned in Section 3 of Canada’s petition, page 4) do not collect information on land area segregated for tame or seeded pasture (pastureland)

. Annual crop surveys collect information on land for pasture, which includes all categories of land in pasture (such as tame/seeded pasture and rangeland) and does not segregate pastures by typ e. Furthermore, the objective of the sample design of annual crop surveys is to estimate field crop areas and yi elds. As a result, the quality

o f estimates for total land in pasture often falls below Statistics Canada ’s data quality standards, and therefore , the estimates are not published. In order to estimate tame or seeded pasture acreage in 2007, the data on tame or seeded pasture are obtained from the past 5 Censuses of Agriculture from 1986 to 2006 and analyzed for the trend. First, the acreage of tame or seeded pasture for these census years is regressed on a constant and a simple linear time trend T , where T varies from 1 to 5 with 1 representing the earliest census year (1986) and 5 representing the latest census year (2006) in the census cycles covered in the analysis. The results show that the data fitted very

well to the linear regression model (Chart 1 and the Summary Output in the attached Excel file). The adjusted R

- square value of the regression, which is a measure of the goodness of fit of data in the regression model and the power of the model in predicting future outcomes, is 0.9367. Inother words, the estimated regression coefficients are capable of explaining about 94% of the variability in the data. E stimates (

Estimate_1 on the worksheet “PastureEst” in the attached Excel file) for the years between census cycle s are derived by adding the immediate past census year’s data to the coefficient of the time trend ( T ) distributed over the years between two successive census ye ars (i.e., the coefficient divided by 5 ). Following the standard practice of benchmarking survey

e stimates for the census years with the census data, the census acreages for tame or seeded pasture are kept unchanged as benchmarks. The annual estimates thus derived have not been smooth over the years. Therefore, a second set of annual estimates ( Estimate_2 in the attached Excel file) is derived by distributing the difference in acreage between two successive censuses over the years within the two censuses. In distributing the differences between 2001 and 2006, both current and immediate past period’s differences have been accounted for at a ratio of 2:1 to keep the estimates at a lower level. The same factor has been used for extrapolatingthe acreage beyond 2006 to derive Estimate_2 for the years 2007

-2010. As evident in

Chart 2 in the attached Excel file, the Estimate_1 and Estimate_2 virtually overlap in all years except the periods 1993

- 1995 and 2004

-2005, and tend to diverge slightly at the end (i.e., after 2008). To avoid higher and lower estimates, a simple average of Estimate_1 and Estimate_2 is taken to derive Estimate_3 , which has been used as the final estimate in Table 5 of Canada’s petition. For EPA’s annual evaluation, annual estimates ( Estimate_3) for tame or seeded pasture areas will be derived from the model. After the publication of census data on tame or seeded pasture in the year following the census year (e.g., 2011 data will be available in 2012), the estimates will be validated with the census data, and if necessary, the model will be reviewed and re

- adjusted.

**Estimates for Christmas tree**  Statistics Canada began collecting data for Christmas tree through the annual survey o f greenhouse, sod and nursery in 200 8

. However, the area data for Christmas tree acreage is not published as the sample frame covers only a subset of farms producing Christmas tree (i.e., only greenhouse and nursery operations that also produce Christmas tree)

. To estimate the Christmas tree, sod and nursery acreage for 2007 , the land area data for Christmas tree are obtained from the Censuses of Agriculture

. Annual data for Christmas tree for the ye ars between census es have been derived by equally distributing the difference in acreage between two successive censuses over the years within the two censuses (Worksheet “XmasTr” in the attached Excel file). The data on sod and nursery acreages have been obtained from annual survey 1 results for years 1997 to 2010, except for 2007, the ye ar for which the data was not published. The sod and nursery acreage for 1996 has been taken from the census data, while that for 1995 has been obtained by subtracting one- fifth of the difference in acreage between 1996 and 2001 from the 1996 acreage. The sod and nursery acreage for 2007 has been estimated as a simple average of 2006 and 2008 data. The total acreages for Christmas tree, sod and nursery thus estimated remained unchanged at 0.2 million acres since 1995 mainly d ue to its lower magnitude and the rounding of decimal points. Therefore, this number is expected to remain unchanged over the short and medium term

. Following the same procedure, annual estimates for Christmas tree, sod and nursery acreage will be derived for EPA’s annual evaluation.

1 There is a lag of one year in nursery and sod survey data collection and publication. The data for the past year are collected through the current year’s survey.