[CTPP] Pareto Interpolation

I previously requested help calculating median family income using the Pareto Interpolation. I appreciate the replies. The attached spreadsheet contains the median family income for towns in South Western Connecticut. The top table shows the values calculated by Pareto Interpolation, and the bottom table illustrates the values calculated by Linear Interpolation. I also calculated the percentage difference between the calculated values and the official Census figures. I confirmed that the difference between the Pareto figures and the Census figures are most likely due to the fact that the Census Bureau calculates median value based upon more detailed distribution information than it releases to the public. Notice that the Pareto calculations are sometimes higher and lower than the official figures, but the linear calculations are higher. Most likely this observation is because Pareto uses a logarithmic curve rather than a straight line. (There may be a few instances where the Pareto figure would be higher than linear.) In addition, the Pareto calculations tend to be more accurate than the Linear ones. I believe the spreadsheet provides a good way to estimate median income values for regions that are not tabulated by the Census. USE AT YOUR OWN RISK. I am not a statistician, and I only have a limited understanding of the formulas. Good luck, Daryl -- Daryl Scott South Western Regional Planning Agency Stamford Government Center 888 Washington Blvd., 3rd Floor Stamford, CT 06901 Tel: (203) 316-5190 Fax: (203) 316-4995 E-mail: dscott(a)swrpa.org