[amelia] Smoothing TSCS Imputed data?

Hi Matt, Thanks again for your help. I am running another issue with Amelia imputation and I hope you can point me to the right direction. I am using Amelia to impute historical CCP party membership and population at the county level. I have used the following Amelia imputation comments, which has specified the TSCS structure and added lags and leads as well as the squared terms to improve the imputation results. a.out=amelia(data, m = 10, idvars = c("province", "prefecture", "county", "prov_id", "pref_id", "sgn_base2", "js_base2", "jcj_base2", "base1", "base2"), ts = "year", cs = "county_id", empri = 100, lags = c("population", "ccp_member"), leads = c("population", "ccp_member"), logs = c("population", "ccp_member","population_sq", "ccp_member_sq", "ccp_branch", "ccp_comission","ccp_branch_sq", "ccp_comission_sq"), polytime=2, incheck = TRUE, max.resample = 1000, tolerance = 0.01) However, the imputed data has very high variance across different years, which defy the patterns that we should have observed in non-missing data. For example, the original party membership with missing value sand the imputed values for one county looks like the following: Year Original Imputed 1938 75 75 1939 588 588 1940 25.15989 1941 29.70148 1942 17.14454 1943 5.593282 1944 35.50387 1945 288.5483 1946 248.8093 1947 82.34441 1948 124.5035 1949 358 358 What worries me is that the imputed party membership jumps up and down so much between 1940 and 1948. I have seen other counties with complete time trend data, I don't think the imputed values in this case are in any way close to the reality. What I can do to smooth the time trend for the imputed values? Any suggestions would be much appreciated. Meanwhile, I have also an unrelated question: how can I only analyze a subset of the imputed data? The "subset" command seems to be incompatible with imputed dataset, as I cannot use the following command "a.out.1945 <- subset(a.out$imputations$year<=1945)" Thanks a ton in advance! Best, Xiaobo -- Xiaobo Lü Associate Professor Department of Government University of Texas at Austin Tel: (512) 232-7257 Fax: (512) 471-1061 Website: www.xiaobolu.com