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:
Guide to Joplin weather in December. The average maximum daytime temperature in Joplin in December is a cool 8Â°C (46Â°F). The average night-time temperature is usually a very cold -3Â°C (27Â°F). There are usually 5 hours of bright sunshine each day, which represents 51% of the 10 hours of daylight.
This week (February 2015) in Missouri, the weather is going to be  cold and snowy. Most days will be in the 30s and 40s, but the  weekend will get a little bit warmer.  â¦ If this isn't the place or the week you wanted to know about,  please ask a question with more specifics, like where you are and  the dates you are asking about.