Given these assumptions, we know the following. 1  The expected value of the difference between all possible sample means is equal to the difference between population means. 2  Thus, E(x 1 - x 2) = Î¼ d = Î¼ 1 - Î¼ 2. 3  The standard deviation of the difference between sample means (Ï d) is approximately equal to:
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Average Weather in Springfield Missouri, United States. Springfield has a warm humid temperate climate with hot summers and no dry season. The temperature typically varies from 26Â°F to 89Â°F over the course of the year, and is rarely below 9Â°F or above 97Â°F. The hot season lasts for 108 days, from June 1 to September 17, with an average daily high temperature above 79Â°F.