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Arithmetic Mean

Arithmetic Mean

What Is the Arithmetic Mean?

The arithmetic mean is the simplest and most widely utilized measure of a mean, or average. It essentially includes taking the sum of a group of numbers, then, at that point, partitioning that sum by the count of the numbers utilized in the series. For instance, take the numbers 34, 44, 56, and 78. The sum is 212. The arithmetic mean is 212 separated by four, or 53.

Individuals likewise utilize several different types of means, for example, the geometric mean and harmonic mean, which becomes possibly the most important factor in certain circumstances in finance and investing. Another model is the trimmed mean, utilized while computing economic data, for example, the consumer price index (CPI) and personal consumption expenditures (PCE).

How the Arithmetic Mean Works

The arithmetic mean keeps up with its place in finance, too. For instance, mean earnings estimates ordinarily are an arithmetic mean. Let's assume you need to know the average earnings expectation of the 16 analysts covering a specific stock. Just include every one of the estimates and separation by 16 to get the arithmetic mean.

The equivalent is true if you have any desire to work out a stock's average closing price during a specific month. Say there are 23 trading days in the month. Essentially take every one of the prices, add them up, and partition by 23 to get the arithmetic mean.

The arithmetic mean is simple, and the vast majority with even a smidgen of finance and math expertise can compute it. It's likewise a valuable measure of central propensity, as it will in general give helpful outcomes, even with large groupings of numbers.

Limitations of the Arithmetic Mean

The arithmetic mean isn't generally great, particularly when a single exception can skew the mean overwhelmingly. Suppose you need to estimate the allowance of a group of 10 kids. Nine of them get an allowance somewhere in the range of $10 and $12 every week. The 10th youngster gets an allowance of $60. That one exception will bring about an arithmetic mean of $16. This isn't extremely representative of the group.

In this specific case, the median allowance of 10 may be a better measure.

The arithmetic mean additionally isn't great while working out the performance of investment portfolios, particularly when it includes compounding, or the reinvestment of dividends and earnings. It is additionally generally not used to work out present and future cash flows, which analysts use in making their estimates. Doing so is practically certain to lead to misleading numbers.


The arithmetic mean can be misleading when there are exceptions or while checking historical returns out. The geometric mean is generally proper for series that exhibit serial correlation. This is particularly true for investment portfolios.

Arithmetic versus Geometric Mean

For these applications, analysts will more often than not utilize the geometric mean, which is calculated in an unexpected way. The geometric mean is generally fitting for series that exhibit serial correlation. This is particularly true for investment portfolios.

Most returns in finance are connected, remembering yields for bonds, stock returns, and market risk premiums. The more drawn out the time horizon, the more basic compounding and the utilization of the geometric mean becomes. For unstable numbers, the geometric average gives an undeniably more accurate measurement of the true return by considering year-over-year compounding.

The geometric mean takes the product of all numbers in the series and raises it to the inverse of the length of the series. It's more relentless manually, however simple to ascertain in Microsoft Excel utilizing the GEOMEAN function.

The geometric mean varies from the arithmetic average, or arithmetic mean, by they way it's calculated on the grounds that it considers the compounding that happens from one period to another. Along these lines, investors as a rule consider the geometric mean a more accurate measure of returns than the arithmetic mean.

Illustration of the Arithmetic versus Geometric Mean

Suppose that a stock's returns over the last five years are 20%, 6%, - 10%, - 1%, and 6%. The arithmetic mean would essentially add those up and partition by five, giving a 4.2% each year average return.

The geometric mean would rather be calculated as (1.2 x 1.06 x 0.9 x 0.99 x 1.06)1/5 - 1 = 3.74% each year average return. Note that the geometric mean, a more accurate calculation in this case, will constantly be more modest than the arithmetic mean.


  • The arithmetic mean is the simple average, or sum of a series of numbers separated by the count of that series of numbers.
  • Different averages utilized all the more normally in finance incorporate the geometric and harmonic mean.
  • In the world of finance, the arithmetic mean isn't typically a suitable method for working out an average, particularly when a single exception can skew the mean overwhelmingly.