Researchers at Dow Chemical Co. investigated the effect of tablet surface area and volume on the rate at which a drug is released in a controlled- release dosage. (Drug Development and Industrial Pharmacy, Vol. 28, 2002.) Six similarly shaped tablets were prepared with different weights and thicknesses and the ratio of surface area to volume was measured for each.

Using a dissolution apparatus, each tablet was placed in 900 milliliters of de-ionized water and the diffusional drug release rate (percentage of drug released divided by the square root of time) determined. The experimental data are listed in the accompanying table.

a. Fit the simple linear model, E(y) = β_o + β₁x, where y = drug release rate and x = surface-are-to-volume ratio.

b. Compute SSE, s², and s.

c. Interpret the value of s.

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DOWDRUG Drug Release Rate Surface Area to Volume (% released/V time) (mm2 /mm) 60 1.50 48 1.05 39 90 33 .75 30 .60 29 .65