Likewise, the formula “=SUMPRODUCT(B2:B3,C2:C3)/SUM(C2:C3)” returns 6.6, which is the weighted average of employee B. The formula “=SUMPRODUCT(A2:A3,C2:C3)/SUM(C2:C3)” returns 7.4, which is the weighted average of employee A. Ignore the double quotation marks of the following entries. The employee with the higher weighted average will be promoted.Ĭells A2 and B2 contain “quality” ratings, while cells A3 and B3 contain “quantity” ratings. The former parameter is assigned 80% weight while the latter is allotted 20% weight.įor ease of understanding, we are considering only two employees (A and B). The resulting products are then summed up and divided by the sum of weights.įor example, the organization Z rates (on a scale of 10) every employee on two parameters, “quality” and “quantity” of the projects delivered. To calculate the weighted average, the numerical values are multiplied by the weights.
With different weights, the importance (or significance) of each value of the dataset differs. The weighted average is used to calculate the average of numerical values that have been assigned different weights. The former measures diversity of a data set (how much the individual numbers differ from each other), while the latter measures the overall (average or typical) level of the data set – whether the numbers (as a whole) are big or small, positive or negative.In Excel, the weighted average is calculated by using the SUMPRODUCT function in the numerator and the SUM function in the denominator. This is why standard deviation is often used together with mean (arithmetic average). In all the examples above, the individual numbers differ from the particular mean of the data set by. The thing which does affect how big or small standard deviation will be is the diversity of the data set – how the individual numbers differ from each other, or from the average (mean) of the data set. So what decides standard deviation being big or small? These all have standard deviation equal to 2.8284 (which is the square root of 8) – assuming we're talking about population, not sample (in such case they would all have standard deviation of 3.1623, which is the square root of 10). It does not even matter whether the individual numbers are big or small as a whole.įor example, the data set has exactly the same standard deviation as the data set and exactly the same standard deviation as the data set or the data set. How negative numbers affect standard deviationįor standard deviation calculation it is not that important whether the individual numbers are positive or negative. Especially in the world of finance, where standard deviation of investment returns is often calculated. In fact, very often you will be calculating standard deviation for data sets which contain both positive and negative numbers (and even some zeroes) at the same time.
#Standard normal table with negatives how to
How to calculate standard deviation of negative numbersĮxactly in the same way you calculate standard deviation for positive numbers, or any numbers. While standard deviation (the result) can't be negative, the individual numbers that you calculate standard deviation for can reach any value, including negative. Can you find standard deviation of negative numbers?
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