how to calculate standard deviation without knowing the mean?
481825
If you know the sample size and sum of the observations, you know the mean but cannot calculate the standard deviation without more information. For example, if you know the values are all 0 or 1 then the sum of the squares is the same as the sum of the observations, so you can compute the standard deviation.
530021
The standard deviation (abbreviated s or SD) is calculated according to the following formula: That is, calculate the deviation from the mean for each point, square those results, sum them, divide by the number of points minus one, and finally take the square root.
1360431
Var = (Mean square) - (Mean)^2 To find the standard deviation, take the square root of the variance. StDev = sqrt(Var) Note that these values are estimates, because with grouped data, you don't have the exact figures to work with.
440893
['Find the mean of the data set. Add all data values and divide by the sample size n.', 'Find the squared difference from the mean for each data value. Subtract the mean from each data value and square the result.', 'Find the sum of all the squared differences. ... ', 'Calculate the variance.']
513195
['Calculate the mean, x.', 'Write a table that subtracts the mean from each observed value.', 'Square each of the differences.', 'Add this column.', 'Divide by n -1 where n is the number of items in the sample This is the variance.']
176802
['Calculate the mean (x̅) of a set of data\u200b', 'Subtract the mean from each point of data to determine (x-x̅). ... ', 'Square each of the resulting numbers to determine (x-x̅)^2. ... ', 'Add the values from the previous step together to get ∑(x-x̅)^2.']
1382947
['Casio fx-991ES.', 'Press to get to the statistics calculation screen. Press (STAT) to see the number of total data points. Press. (STAT) to see the mean x . Press. (STAT) to see the standard deviation. −', 'nx. σ', '.', 'STAT. SHIFT. = AC. SETUP. arrow keys. MODE.']
11944
['Work out the Mean (the simple average of the numbers)', 'Then for each number: subtract the Mean and square the result.', 'Then work out the mean of those squared differences.', 'Take the square root of that and we are done!']
1250446
['Find a mean of the set of data.', 'Subtract each number from a mean.', 'Square the result.', 'Add the results together.', 'Divide a result by the total number of numbers in the data set.']
237171
To figure out the variance, subtract 82.5 from the mean, which is 5.5 and then divide by N, which is the value of numbers, (in this case 10) minus 1. The result is a variance of about 9.17. Standard deviation is the square root of the variance so that the standard deviation would be about 3.03.
394878
So the more spread out the group of numbers are, the higher the standard deviation. To calculate standard deviation, add up all the data points and divide by the number of data points, calculate the variance for each data point and then find the square root of the variance.
1252459
['Calculate the mean (simple average of the numbers).', 'For each number: subtract the mean. ... ', 'Add up all of the squared results.', 'Divide this sum by one less than the number of data points (N - 1).']
47935
['Calculate the mean or average of each data set. ... ', 'Subtract the deviance of each piece of data by subtracting the mean from each number. ... ', 'Square each of the deviations.', 'Add up all of the squared deviations.', 'Divide this number by one less than the number of items in the data set.']
399889
Step 1: Calculate the mean (Total of all samples divided by the number of samples). Step 2: Calculate each measurement's deviation from the mean (Mean minus the individual measurement). ... Step 7: Divide the standard deviation by the square root of the sample size (n). That gives you the “standard error”.
1226959
['Mean = Sum_of_each_individual/Total_number_of_items.', 'Variance = ((Original_Value – Mean)² + (Original_Value – Mean)² +.... )/(Total_number_of_items - 1)', 'Standard_Deviation = Square_root (Variance)']
963714
['Calculate the mean of your data set.', 'Subtract that mean from each of the scores in your data set to determine the individual deviation of each score from the mean.', 'Square each of those individual deviations.', 'Sum all of the squared deviations.', 'Divide that sum by one less than the sample size (N–1)']
193276
['Work out the Mean (the simple average of the numbers)', 'Then for each number: subtract the Mean and square the result (the squared difference).', 'Then work out the average of those squared differences. (Why Square?)']