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First, the concept of standard deviation

Standard deviation (Standard deviation), the average number of distances from which each data deviates from the average, which is the square root of the deviation squared and the average. expressed in Σ. Therefore, the standard deviation is also an average

The standard deviation is the arithmetic square root of the variance. Standard deviation can reflect the degree of dispersion of a dataset. The average is the same, and the standard deviation is not necessarily the same.

Let's look at the data table below first.

In the table above, the arithmetic average for both sets of data is 71, but their standard deviation is not the same.

The following figure is the standard deviation for AB two sets of data.

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As a result, we can see that the greater the value of the standard deviation, the greater the gap between the data of the group.

For the students ' grades, the higher the standard deviation, the greater the gap between students. The same is true of others.

Second, DStDevP function knowledge extension

Function: Calculates the overall standard deviation of the population of a list or database that satisfies a specified condition in a column.

Grammar

DSTDEVP (Database,field,criteria)

The database makes up the range of cells in the list or the databases. A database is a list of related data that contains the behavior records of the related information and the column fields that contain the data. The first line of the list contains the flags for each column.

field specifies the data column used by the function. The data column in the list must have a flag item in the first row. field can be text, which is a quoted item at both ends, such as "years of use" or "output", and field can also be a number that represents the position of the data column in the list: 1 for the first column, 2 for the second column, and so on.

Criteria is a set of ranges of cells that contain the given criteria. You can specify any range for the argument criteria, as long as it contains at least one column label and the cell below the column label to set the criteria.

Third, the standard deviation in the use of foreign exchange

Standard deviation is a statistic used to measure the degree to which a value in a set of values differs from its average. The standard deviation is used to assess the possible change or volatility of the price. The greater the standard deviation, the wider the range of price fluctuations, and the greater the volatility of financial instruments.

Elaboration and application

In simple terms, standard deviation is a measure of the degree to which a set of values is dispersed from the average. A larger standard deviation, representing the large difference between the majority of the value and its average, and a smaller standard deviation, representing these values closer to the average.

For example, the sets of two sets of numbers {0, 5, 9, 14} and {5, 6, 8, 9} have an average of 7, but the second set has a smaller standard deviation.

Standard deviation can be used as a measure of uncertainty. For example, in physical science, the standard deviation of a set of values represents the accuracy of these measurements when doing repetitive measurements. When determining whether the measured value conforms to the predicted value, the standard deviation of the measured value plays a decisive role: if the measured mean is too far apart from the predicted value (and compared to the standard deviation value), the measured value is considered contradictory to the predicted value. This is easy to understand, because if the measured value falls outside a certain numerical range, it is reasonable to infer whether the predicted value is correct.

The standard deviation is applied to investment and can be used as an indicator to measure the stability of returns. The higher the standard deviation value, the higher the risk of the return than the average value of the past and the less stable returns. On the contrary, the finer the standard deviation value, the more stable the representative returns and the less risk.

Sample standard deviation in the real world, unless in some special circumstances, it is unrealistic to find the true standard deviation of a whole. In most cases, the overall standard deviation is calculated by randomly sampling a certain amount of sample and calculating the standard deviation of the sample.

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