an estimated margin. The procedure to develop the margin estimates involved the following steps: First, estimate regression coefficients for equation [4]. [4] Pi = a + #'P: + i-Qi +PTi i = 1, 2, ..., n P is the retail price, P* is the FOB price, Q is the quantity sold and assumed to be equal at retail and FOB, and T is time. Second, subtract P.* from each side of equation [4] and 1 define P. P* as the wholesale-retail margin, M.. 1 1 1 Thus, [5] Mi = a +(p. 1)Pi* + p2Qi + pITi i = 1, 2, ..., n This procedure was carried out for frozen concentrated orange juice, canned single strength orange juice, and chilled orange juice with monthly data, October 1961 to September 1967. The coefficients for the margin equations are given in Table 5. The functions for these three products at the FOB level were derived by subtracting the appropriate margin from each of the functions estimated at the retail level, equations [1] through [3]. This procedure provided the following empirical FOB equations in natural numbers: a. Frozen concentrated orange juice [6] P* FCOJ = 54.161 543.073Q FCOJ 89.894Q CssoJ + 522.450Q coJ 1053.989Q cssGJ + .049T .012Y b. Chilled orange juice [7] P* coJ = 131.03 3462.74Q coJ 2130.09Q FCOJ 962.32Q cssoJ 8570.16Q CSSGJ + 1.286T .014Y c. Canned single strength orange juice [8] P* cssoJ = 116.859 153.615Q cssoJ 494.646Q FcoJ 1275.612Q coJ 4641.521Q cssGJ + .147T .027Y The price flexibility estimate for frozen concentrated orange juice is a negative .883 at the FOB level. This is more flexible than the price flexibilities estimated at retail by equation [1], as would be expected from the theory of derived demand, assuming linear estimation in natural numbers. The price flex- ibility estimate for chilled orange juice is a negative .610, which is also more flexible than the estimate at retail by equation [2]. On the other hand, the price flexibility for canned single strength juice is a negative .122, which is less flexible than was estimated at retail by equation [3]. This result was not anticipated.