Calculate Standard Deviation and Standard Error

                                                                    

 

Standard deviation and standard error are the most important topics of math & statistics and play an exclusive role in finding the dispersion and accuracy of data for different data set values. Standard deviation helps to find the dispersion of the data and gives information on how much the values are dispersed from its mean.

 

The standard error is used to estimate the precision of a sample that represents the population of the given data and its variability for different sample sizes. Standard deviation and standard error calculation are important for data analysis in statistics.

In this comprehensive guide, we will explain the basic definitions of standard deviation and standard error, provide their formulas, demonstrate methods to calculate these values, and explain their importance for data analysis. If you're looking for more statistical tools, you might find the online percentage calculator quite handy for various calculations.

 

What is Standard Deviation?

 

Standard deviation is the amount that shows how much the value is dispersed from its mean. It is a well-known measure of variability because it returns the original unit of measurement. It is abbreviated by the symbol “Std Dev & SD” and its mathematical formula can be written as below depending on the data set size such as sample & population.

 

For a population data set:

 

σ = √ 1​/n ∑ i=1n​(Xi​−μ)2

​

For sample data set:

 

S = √ 1​/ (n-1) ∑ i=1n​(Xi​−μ)2

​

Where:

 

  • Xi = terms of the data set (X1, X2, X3,…., Xn)
  • μ = mean of data,
  • n = number of data sets,
  • σ = standard deviation value for population (known as sigma sign)
  • ​(Xi​−μ)2​= value of the sum of square

 

The smaller value of standard deviation shows the data points are close to the mean, while a high value represents the data points that are spread away from the mean of the data set.

 

How to Calculate the Standard Deviation?

 

To find the numerical value of the standard deviation, follow the below steps:

 

  • Find the Mean (Average): First, find the mean of the given data set by summing all the data points and dividing it by the number of data points (n). Its formula can be written as:

 

Mean (μ)=∑i=1nXi/n

 

  • Find the Sum of Squares: Now, subtract the mean from each data point and square the result, then sum all the squared results. After that, divide the sum by the number of data points “n” (for a population) and “n-1” (for a sample).

 

For population:

 

1/n [∑ i=1n​(Xi​−μ)2] ​= 1/n [​(X1​−μ)2+ ​(X2​−μ)2+​(X3​−μ)2+…+​(Xn​−μ)2]

 

For sample:

 

1/(n-1) [∑ i=1n​(Xi​−μ)2] ​= (1/n-1) [​(X1​−μ)2+ ​(X2​−μ)2+​(X3​−μ)2+…+​(Xn​−μ)2]

 

  • Standard Deviation: Finally, put the values in the standard deviation formula according to its data points/data set and take the square root of all values after simplification.

 

For a population data set:

 

σ = √ 1​/n ∑ i=1n​(Xi​−μ)2​

 

For sample data set:

 

σ = √ 1​/ (n-1) ∑ i=1n​(Xi​−μ)2​

 

For a better understanding of the above steps, we provide a practical example with detailed steps that help to understand the calculation of standard deviation.

 

Example of Standard Deviation: 

 

If the sample data set is given as {2, 10, 8, 6, 4} then calculate the standard deviation of the dataset.

 

Solution:

 

For the standard deviation value, we first find the mean & sum of squares values of the given data set.

 

Step 1: Arrange the sample data and find the mean value by its formula.

 

Sample data = {2, 4, 6, 8, 10}, Number of elements = 5

 

 μ =∑i=1nXi/n = (X1 + X2 +X3 +X4 + X5)/n 

 

        = (2 + 4 + 6 + 8 + 10)/5 = 30/5 = 6

 

Step 2: Now, find the Sum of Squares by subtracting each data set point from its mean and dividing its value by its size for the sample data points. 

 

1/(n-1) [∑ i=1n​(Xi​−μ)2] ​= (1/n-1) [​(X1​−μ)2+ ​(X2​−μ)2+​(X3​−μ)2+…+​(Xn​−μ)2]

 

          = 1/(5-1) {(2 − 6)2+ (4 − 6)2+ (6 − 6)2+ (8 − 6)2+ (10 − 6)2} 

 

          =1/4 {16 + 4 + 0 + 4 + 16} = 1/4 {40} = 10

 

Step 3: Finally, put the values in the SD formula for a sample and simplify by taking the square root of the terms.

 

S = √ 1​/ (n-1) ∑ i=1n​(Xi​−μ)2​

 

S = √ 10 ​ = 3.162

 

To overcome from above long manual calculation method, use the standard deviation calculator for the calculation of the standard deviation of your sample/population data set, by just putting the data set values in the input fields of this calculator and getting accurate results in seconds.

 

                                                     

 

What is Standard Error?

 

Standard error is a measure of the accuracy with that sample which represents a population. It indicates how much variability there is in the sample mean from sample to sample. It also measures the accuracy for those distributions that represent its population by using standard deviation. 

Standard error is inversely proportional to the sample size, if the sample size is large then the standard error value will be smaller because the statistical value will approach the actual value. It's simple notation is “SE” and the mathematical formula can be represented as:

 

SE = σ/√n

 

Where:

 

  • σ = standard deviation of the sample.
  • n = number of data points in the sample.

 

The smaller value of SE shows that the sample mean is a more precise estimate of the population mean and improves the reliability of the statistical results. It is used in hypothesis testing and confidence interval estimation to determine the margin of error and the significance of the results.

 

How to calculate the Standard Error?

 

To calculate the standard error by its formula follow the below steps.

  • Find the standard deviation if it is not given by following the above steps.
  • Note the number of elements of the given data set.
  • Put the values in its formula and simplify it using the division rule.

Here, we solved the mathematical example for a better understanding of the above steps.

 

Example of Standard Error

 

If the standard deviation is 2.83 and the sample size of the data set is “6” then calculate the Standard error of given data.

Solution:

 

Step 1: Write the given data from the given question.

 

σ = 2.83, n = 6

 

Step 2: Put the values in the SE-formula.

 

SE = σ/√n = 2.83/√6 = 2.83/2.45 

 

 SE = 1.15

 

                                                                                          

 

To find the value of standard error with a fast and accurate method use the Standard Error Calculator by Allmath which provides the answer of your data in minor seconds.

 

Significance of Standard Deviation and Standard Error

 

  • Standard Deviation: It helps to understand the spread of data around the mean and compare the separation of different datasets according to the mean.

 

  • Standard Error: It provides information about how precisely the sample mean represents the population mean. A smaller SE indicates that the sample mean is a more accurate estimate of the population mean.

 

Wrap up

 

SD and SE both are necessary for mathematics and statistics. Standard deviation helps us to understand the variability of your data about the mean while standard error helps us the reliability of the sample mean for the given population. 

 

In this guide, we provided a clear explanation of standard deviation and standard error, including their definitions, formulas, and significance. By mastering these concepts, you have to analyze your data and make accurate decisions based on your results.