CIs for the Cost-effectiveness ratio CECI is a program to calculate confidence intervals for the cost-effectiveness ratio. The present program was de- veloped by Herman Ader. The program can produce confidence intervals for the cost- effectiveness ratio, computed according to different approaches: 1. The proposal by Wakker and Klaassen (1995) 2. The proposal of O'Brien, Drummond, Labelle, and Willan (1994). 3. Using Fieller's formula, with and without taking corre- lations between costs and effects into account (Fieller, 1954). 4. By bootstrapping, using the bias-corrected percentile method (Stinnett, 1996\; Chaudhary &amp\; Stearns, 1996) In case bootstrapping is specified, the program produces a file with the generated cost- and effect differences and the corresponding ratio. This file can be used to draw acceptability curves. REFERENCES ----------Chaudhary, M. A., &amp\; Stearns, S. C. (1996). Estimating confi- dence intervals for cost-effectiveness ratios: An example from a randomized trial. Statistics in Medicine, 15, 1447- 1458. (Letter to the Editor) O'Brien, B. J., Drummond, M. F., Labelle, R. J., &amp\; Willan, A. (1994). In search of power and significance: Issues in the design and analysis of stochastic cost-effectiveness studies in health care. Medical Care, 32, 150-163. Stinnett, A. A. (1996). Adjusting for bias in C/E ratio estimates. Health Economics, 5, 470-472. Wakker, P., &amp\; Klaassen, M. P. (1995). Confidence intervals for Cost/Effectiveness ratios. Health Economics, 4, 373-381. Willan, A. R., &amp\; O'Brien, B. J. (1996). Confidence intervals for Cost-effectiveness ratios: an applicatino of Fieller's theorem. Health Economics, 5, 297-305.