What is the difference between STDEV.S and STDEV.P?
(a) STDEV.S calculates standard deviation of a sample; STDEV.P calculates the standard deviation of a population.
(b) STDEV.P calculates the standard deviation of a population; STDEV.S calculates average variation.
(c) STDEV.P calculates the standard deviation of a population; STDEV.S calculates variance.
(d) There is no difference.
The Correct Answer and Explanation is :
The correct answer is: **(a) STDEV.S calculates the standard deviation of a sample; STDEV.P calculates the standard deviation of a population.**
In statistical analysis, standard deviation quantifies the dispersion or variability of a dataset relative to its mean. Microsoft Excel provides two distinct functions to compute standard deviation, tailored to the nature of your dataset:
- **STDEV.S (Sample Standard Deviation):**
- Purpose: Calculates the standard deviation for a sample subset of a larger population.
- **Formula:** s=∑i=1n(xi−xˉ)2n−1s = \sqrt{\frac{\sum_{i=1}^n (x_i – \bar{x})^2}{n – 1}}
- ss: Sample standard deviation
- nn: Sample size
- xix_i: Each individual observation
- xˉ\bar{x}: Sample mean
- Usage: Employ STDEV.S when your data represents a sample, and you aim to infer the standard deviation of the entire population. Dividing by n−1n – 1 (Bessel’s correction) provides an unbiased estimate, compensating for the fact that the sample mean is an estimate of the population mean.
- **STDEV.P (Population Standard Deviation):**
- Purpose: Calculates the standard deviation for an entire population dataset.
- **Formula:** σ=∑i=1N(xi−μ)2N\sigma = \sqrt{\frac{\sum_{i=1}^N (x_i – \mu)^2}{N}}
- σ\sigma: Population standard deviation
- NN: Population size
- xix_i: Each individual observation
- μ\mu: Population mean
- Usage: Use STDEV.P when your dataset encompasses the entire population. Dividing by NN provides the exact standard deviation without the need for correction, as there’s no estimation involved.
Key Differences:
- **Denominator Adjustment:**
- STDEV.S divides by n−1n – 1 to correct bias in the estimation of the population standard deviation from a sample.
- STDEV.P divides by NN since it deals with the full population, requiring no correction.
- **Application Context:**
- STDEV.S: Appropriate for sample data, providing an estimate of the population’s standard deviation.
- STDEV.P: Suitable for complete population data, yielding the actual standard deviation.
Practical Implications:
Choosing the correct function is crucial for accurate statistical analysis. Applying STDEV.P to sample data can underestimate variability, while using STDEV.S for population data can overestimate it. Understanding your dataset’s scope ensures the selection of the appropriate function, leading to valid and reliable results.
For a more in-depth understanding, you might find the following video helpful:
videoUnderstanding Sample (STDEV.S) and Population (STDEV.P) Standard Deviation in Excelturn0search11