In: Statistics and Probability
You are trying to develop a strategy for investing in two different stocks. The anticipated annual return for a $1,000 investment in each stock under four different economic conditions has the probability distribution shown to the right. Complete parts (a) through (c) below. Probability Economic_condition
Stock_X Stock_Y A. Compute the expected return for stock X and for stock Y. The expected return for stock X is (Type an integer or a decimal. Do not round.) The expected return for stock Y is (Type an integer or a decimal. Do not round.) B. Compute the standard deviation for stock X and for stock Y. The standard deviation for stock X is (Round to two decimal places as needed.) The standard deviation for stock Y is (Round to two decimal places as needed.) C. Would you invest in stock X or stock Y? Explain. Choose the correct answer below. A.Since the expected values are approximately the same, either stock can be invested in. However, stockX has a larger standard deviation, which results in a higher risk. Due to the higher risk of stockX, stockY should be invested in. B.Since the expected values are approximately the same, either stock can be invested in. However, stockY has a larger standard deviation, which results in a higher risk. Due to the higher risk of stock Y,stockX should be invested in.Your answer is not correct. C.Based on the expected value, stockY should be chosen. However, stockY has a larger standard deviation, resulting in a higher risk, which should be taken into consideration. D.Based on the expected value, stockX should be chosen. However, stockX has a larger standard deviation, resulting in a higher risk, which should be taken into consideration. |
Answer A. First, let's just recreate the table to look like this:
Probability | Economic Condition | Stock_X | Stock_Y |
0.1 | Recession | -90 | -170 |
0.3 | Slow_growth | 20 | 50 |
0.4 | Moderate_growth | 110 | 150 |
0.2 | Fast_growth | 160 | 190 |
Now, let's try to understand the table and then I'll explain the terms given in the question. There are 4 economic periods and their respective probabilities of happening are known. Then, the respective returns that each of stock X and y would give in these respective economic conditions is also known. Annual returns are usually expressed in a percentage form. Thus, we change them to a decimal format for easy calculations.
Probability | Economic Condition | Stock_X | Stock_Y |
0.1 | Recession | -0.9 | -1.7 |
0.3 | Slow_growth | 0.2 | 0.5 |
0.4 | Moderate_growth | 1.1 | 1.5 |
0.2 | Fast_growth | 1.6 | 1.9 |
Now, we need to calculate the expected return on Stock X. This is the return that an individual expects a stock to earn over the next period. Of course, because this is only an expectation, the actual return may be either higher or lower. An individual’s expectation may simply be the average return per period a security has earned in the past.
Thus, we calculate the weighted average of the returns of Stock X in each of the conditions
Estimated return on Stock X = (0.1*(-0.9)) + (0.2*0.3) + (1.1*0.4) + (1.6*0.2)/4 = 0.1825 = 18.25%
Estimated return on Stock Y = (0.1*(-1.7)) + (0.3*0.5) + (0.4*1.5) + (0.2*1.9)/4 = 0.24 = 24%
B. Standard Deviation
For each stock, calculate the deviation of each possible return from the stock’s expected return given previously.
The deviations we have calculated are indications of the dispersion of returns. However, because some are positive and some are negative, it is difficult to work with them in this form. For example, if we were to simply add up all the deviations for a single company, we would get zero as the sum. To make the deviations more meaningful, we multiply each one by itself. Now all the numbers are positive, implying that their sum must be positive as well.
For each stock, calculate the average squared deviation, which is the variance:
Economic Condition | Rate of Return | Deviation from Expected return | Squared value of Deviation |
Recession | -0.9 | -1.0825 | 1.17180625 |
Slow_growth | 0.2 | 0.0175 | 0.00030625 |
Moderate_growth | 1.1 | 0.9175 | 0.84180625 |
Fast_growth | 1.6 | 1.4175 | 2.00930625 |
Average of Squared Deviations | 1.00580625 |
Expected rate of return | 0.1825 |
Thus, the variance of the returns on Stock X is 1.0058
Now, we know that standard deviation is calculated as the square root of the variance = = 1.003 approx, which is 100% approx.
Now, for stock Y, we do the same calculations
Economic Condition | Rate of Return | Deviation from Expected return | Squared value of Deviation |
Recession | -1.7 | -1.94 | 3.7636 |
Slow_growth | 0.5 | 0.26 | 0.0676 |
Moderate_growth | 1.5 | 1.26 | 1.5876 |
Fast_growth | 1.9 | 1.66 | 2.7556 |
Average of Squared Deviations | 2.0436 |
Expected rate of return | 0.24 |
Standard Deviation for Stock Y is given as = 143% approx
C. The expected values for both Stock X and Stock Y are not the same. Thus, options A and B are ruled out automatically. Based on the exptected returns, Stock Y gives a higher return i.e. 24%. However, it has a higher standard deviation that Stock X, which means higher risk. Thus, Option C is the correct answer.