![]() Value (X)Īs the data is not given as sample data, thus we use the formula for population variance. Step 2: Make a table as following with three columns, one for the X values, the second for the deviations and the third for squared deviations. Step 1: First compute the mean of the 10 values given. Μ is the mean value equal to E(X), so the above equation may also be expressed as, This means that variance is the expectation of the deviation of a given random set of data from its mean value and then squared. ![]() Variance Formulaįor the purpose of solving questions, it is, Other examples of population and samples would be the total members of a school versus only the members of a class in the school or a random selection of 50 members of a school, which will also be a sample. If we collect data on the members of our household and only collect data about two members out of the five members. A sample is a part of the population used to describe the whole group. If we were to collect data on just the members of our household, then everyone living in would be considered the population. Population is having all members of a specified group. There are two types of variance, one is population and the other is a sample. ![]() We show these differences in data by using variance. Although both sets of data have an average of ten. We can notice that there is a greater difference between the numbers in the second set of data versus the first set of data. Now take a look at this set of data: 28, 4, 6, 4, 2, 16. ![]() Notice that these numbers are all pretty close to the number 10. If we add these numbers together and divide by the total numbers in the data set, which in this case is 6, you will get an average of 10. For example, take a look at the following numbers: 12, 8, 10, 10, 8, 12. This is different from finding the average, or the mean, of numbers. Variance is used in how far a set of numbers are spread out. Note that the shipping departments total static budget variance is 8,000 unfavorable since the actual expenses of 508,000 were more than the static budget of 500,000. 2 Solved Examples Variance Formula What is a Variance? ![]()
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