Generalised variance functions for longitudinal survey data

Figures & data

Figure 1. U.S. population from 1900 to 2010.

Figure 2. Logs of estimates of relvar plotted versus logs of population totals.

Figure 3. Ratio of the SEs (LGVF1–LGVF2/relvar) versus log (totals).

Figure 4. Logs of estimates of relvar plotted versus logs of population totals.

Figure 5. Ratio of the SEs (LGVF1–LGVF3/relvar) versus log(totals).

Figure 6. Logs of predicted relvar by using LGVF1–3 plotted versus logs of population totals (11 March).

Table 1. Comparison of GVF and LGVF.

		GVF	LGVF
Predicting 5 left out variables	Method 1	0.02183022	0.01636561
(2011)	Method 2	0.02110222	0.01724829
	Method 3	0.01754491	0.01619439
Predicting 19 variables	Method 1	0.01781202	0.00898679
(2011, 14 grouping, 5 left out for GVF)	Method 2	0.01811376	0.00310806
(19 left out for LGVF)	Method 3	0.02436289	0.01057787

Notes: Numbers in the table are the square root of mean-squared predicted errors. Method 1 is ordinary least-squares fitting, Method 2 is weighted least-squares fitting, and Method 3 is log transformation on both y and x fitting.