Researchers at the Oak Ridge (Tennessee) National Laboratory have developed an algorithm to estimate the numbers of expected and excess cases of thyroid cancer occurring in the lifetime of those exposed to atomic weapons tests at the Nevada Test Site in the 1950s (Health Physics, Jan. 1986). Of the approximately 23,000 people exposed to the weapons-testing fallout, 58 were expected to develop thyroid cancer in their remaining lifetimes. According to the algorithm, the 58 cases can be categorized by sex and level of radiation (dose) at the time of exposure as shown in the table. Suppose that the data represent a random sample of 58 thyroid cancer patients selected from the target population. Conduct a test to determine whether the two directions of classification, sex and dose at time of exposure, are independent. Use α = .01.

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АТОМIС Gender Male Female ТOTALS Less than 1 6. 13 19 Dose, rad 1-10 8 18 26 11 or more 3 10 13 ТОТALS 17 41 58