please explain standard deviation?

Question

I have never heard of it before yet I have to incorporate it into my lab results and make an excel spread sheet with it.

Answer 1

Excel will compute mean and standard deviation from a column or row of numbers. Look under statistical functions. Standard deviation is a measure of the "scatter" of values in a collection of numbers. Do not confuse with variance, also a measure of scatter; Std Dev is the square root of variance. The advantage of Std Dev is that it has the same units (dimension) as the data.

Answer 2

The square root of the average of the squares of deviations about the mean of a set of data. Standard deviation is a statistical measure of spread or variability

Standard deviation
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In probability and statistics, the standard deviation of a probability distribution, random variable, or population or multiset of values is defined as the square root of the variance.

The standard deviation is measured in the same units as the values of the population. For a population of distances in meters, the standard deviation is also measured in meters, whereas the variance is measured in square meters.

At least 75% of the values in any population are within two standard deviations away from the mean. See Chebyshev's inequality. Approximately 95% of the values in a population having normal distribution are within two standard deviations away from the mean.

The term standard deviation was introduced to statistics by Karl Pearson On the dissection of asymmetrical frequency curves, 1894.

The standard deviation is the root mean square (RMS) deviation of the values from their arithmetic mean. For example, in the population (4, 8), the mean is 6 and the standard deviation is 2. This may be written: (4, 8) ≈ 6±2. In this case 100% of the values in the population are within two standard deviations away from the mean.

Standard deviation is the most common measure of statistical dispersion, measuring how spread out the values in a data set are. If the data points are all close to the mean, then the standard deviation is close to zero. If many data points are far from the mean, then the standard deviation is far from zero. If all the data values are equal, then the standard deviation is zero.

The standard deviation (σ) of a population can be estimated by a modified standard deviation (s) of a sample. The formulae are given below

Answer 3

Standard deviation is a measure of statistical dispersion, measuring how spread out the values are. If the data points are all close to the mean, then the standard deviation is close to zero. If many data points are far from the mean, then the standard deviation is far from zero. If all the data values are equal, then the standard deviation is zero.

http://en.wikipedia.org/wiki/Standard_deviation

Answer 4

1. a measure of the dispersion of a frequency distribution that is the square root of the arithmetic mean of the squares of the deviation of each of the class frequencies from the arithmetic mean of the frequency distribution; also : a similar quantity found by dividing by one less than the number of squares in the sum of squares instead of taking the arithmetic mean
2 : a parameter that indicates the way in which a probability function or a probability density function is centered around its mean and that is equal to the square root of the moment in which the deviation from the mean is squared

Answer 5

Here is the address of a website that explains it with practical examples.

Standard Deviation
A simple explanation of standard deviation, for journalists and other writers who might not know math.
http://www.robertniles.com/stats/stdev.shtml

Good luck
Dragonsdy