## Excel 2010 Financials Cookbook

Powerful techniques for financial organization, analysis, and presentation in Microsoft Excel

Till now, in the previous articles, we have focused on manipulating data within and outside of Excel in order to prepare to make financial decisions. Now that the data has been prepared, re-arranged, or otherwise adjusted, we are able to leverage the functions within Excel to make actual decisions. Utilizing these functions and the individual scenarios, we will be able to effectively eliminate the uncertainty due to poor analysis. Since this article utilizes financial scenarios for demonstrating the use of the various functions, it is important to note that these scenarios take certain “unknowns” for granted, and makes a number of assumptions in order to minimize the complexity of the calculation. Real-world scenarios will require a greater focus on calculating and accounting for all variables.

# Determining standard deviation for assessing risk

In the recipes mentioned so far, we have shown the importance of monitoring and analyzing frequency to determine the likelihood that an event will occur. Standard deviation will now allow for an analysis of the frequency in a different manner, or more specifically, through variance. With standard deviation, we will be able to determine the basic top and bottom thresholds of data, and plot general movement within that threshold to determine the variance within the data range. This variance will allow the calculation of risk within investments.

As a financial manager, you must determine the risk associated with investing capital in order to gain a return. In this particular instance, you will invest in stock. In order to minimize loss of investment capital, you must determine the risk associated between investing between two different stocks, Stock A, and Stock B.

In this recipe, we will utilize standard deviation to determine which stock, either A or B, presents a higher risk, and hence a greater risk of loss.

## How to do it…

We will begin by entering the selling prices of Stock A and Stock B in columns A and B, respectively:

Within this list of selling prices, at first glance we can see that Stock B has a higher selling price. The stock opening price and selling price over the course of 52 weeks almost always remains above that of Stock A. As an investor looking to gain a higher return, we may wish to choose Stock B based on this cursory review; however, high selling price does not negate the need for consistency.

1. In cell C2, enter the formula =STDEV(A2:A53) and press Enter:

2. In cell C3, enter the formula =STDEV(B2:B53) and press Enter:

We can see from the calculation of standard deviation, that Stock B has a deviation range or variance of over \$20, whereas Stock A’s variance is just over \$9:

Given this information, we can determine that Stock A presents a lower risk than Stock B. If we invest in Stock A, at any given time, utilizing past performance, our average risk of loss is \$9, whereas in Stock B we an average risk of \$20.

## How it works…

The function of STDEV or standard deviation in Excel utilizes the given numbers as a complete population. This means that it does not account for any other changes or unknowns. Excel will use this data set as a complete set and determine the greatest change from high to low within the numbers. This range of change is your standard deviation. Excel also includes the function STDEVP that treats the data as a selection of a larger population. This function should be sed if you are calculating standard deviation on a subset of data (for example, six months out of an entire year).

If we translate these numbers into a line graph with standard deviation bars, as shown in the following screenshot for Stock A, you can see the selling prices of the stock, and how they travel within the deviation range:

If we translate these numbers into a line graph with standard deviation bars, as shown in the following screenshot for Stock B, you can see the selling prices of the stock, and understand how they travel within the deviation range:

The bars shown on the graphs represent the standard deviation as calculated by Excel. We can see visually that not only does Stock B represent a greater risk with the larger deviation, but also many of the stock prices fall below our deviation, representing further risk to the investor.

With funds to invest as a finance manager, Stock A represents a lower risk investment.

## There’s more…

Standard deviation can be calculated for almost any data set. For this recipe, we calculated deviation over the course of one year; however, if we expand the data to include multiple years we can further determine long-term risk. While Stock B represents high short-term risk, in the long-term analysis, Stock B may present as a less risky investment. Combining standard deviation with a five-number summary analysis, we can further gain risk and performance information.

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