Performance of stock screeners.Investment companies provide their clients with automated tools—called stock screeners—to help them select a portfolio of stocks to invest in. The American Association of Individual Investors (AAII) provides statistics on stock screeners at its Website, www.aaii.com. The next table lists the annualized percentage return on investment (as compared to the Standard & Poor’s 500 Index) for 13 randomly selected stock screeners. (Note:A negative annualized return reflects a stock portfolio that performed worse than the S&P 500.)

(9.0, -.1, -1.6, 14.6, 16.0, 7.7, 19.9, 9.8, 3.2, 24.8, 17.6, 10.7, 9.1)

a.Compute the mean for the data set. Interpret its value.

b.Compute the median for the data set. Interpret its value.

Short Answer

Expert verified

a) Mean = 10.82

b) Median = 9.8

Step by step solution

01

Computing and Interpreting the Mean

Mean=SumofallvaluesNumberofvalues

Mean=9.0+-1+-1.6+14.6+16.0+7.7+19.9+9.8+3.2+24.8+17.6+10.7+9.113=140.713=10.82

As the mean is 10.82, the average annualized percentage return on investments is 10.82%for a portfolio of 13 stocks that were randomly selected.

02

Calculating and Analyzing the Median

By arranging the data in ascending order we get,

(-1.6, -0.1, 3.2, 7.7, 9.0, 9.1, 9.8, 10.7, 14.6, 16.0, 17.6, 19.9, 24.8)

9.8 lies in the middle of the distribution. Hence, 9.8 is the median.

Half of the annualized percentage return on investment is less than 9.8, and half is more than 9.8.

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Most popular questions from this chapter

Network server downtime.A manufacturer of network computer server systems is interested in improving its customer support services. As a first step, its marketing department has been charged with the responsibility of summarizing the extent of customer problems in terms of system downtime. The 40 most recent customers were surveyed to determine the amount of downtime (in hours) they had experienced during the previous month. These data are listed in the table.

Customer Number

Downtime

Customer Number

Downtime

230

12

250

4

231

16

251

10

232

5

252

15

233

16

253

7

234

21

254

20

235

29

255

9

236

38

256

22

237

14

257

18

238

47

258

28

239

0

259

19

240

24

260

34

241

15

261

26

242

13

262

17

243

8

263

11

244

2

264

64

245

11

265

19

246

22

266

18

247

17

267

24

248

31

268

49

249

10

269

50

a.Construct a box plot for these data. Use the information reflected in the box plot to describe the frequency distribution of the data set. Your description should address central tendency, variation, and skewness.

b.Use your box plot to determine which customers are having unusually lengthy downtimes.

c.Find and interpret the z-scores associated with the customers you identified in part b.

The economic return to earning an MBA. Refer to the International Economic Review (August 2008) study on the economic rewards to obtaining an MBA degree, Exercise 1.27 (p. 51). Job status information was collected for a sample of 3,244 individuals who sat for the GMAT in each of four time periods (waves). Summary information (number of individuals) for Wave 1 (at the time of taking the GMAT) and Wave 4 (7 years later) is provided in the accompanying table. Use a graph to compare and contrast the job status distributions of GMAT takers in Wave 1 and Wave 4.

Job Status

Wave 1

Wave 4

Working, No MBA

2,657

1,787

Working, Have MBA

0

1,372

Not Working, Business School

0

7

Not Working, Other
Graduate School

36

78

Not Working, 4-Year
Institution

551

0

Total

3,244

3,244

Compute xbar, s2, and sfor each of the following data sets. If appropriate, specify the units in which your answer is expressed.

a.3, 1, 10, 10, 4

b.8 feet, 10 feet, 32 feet, 5 feet

c.-1, -4, -3, 1, -4, -4

d.1/5 ounce, 1/5 ounce, 1/5 ounce, 2/5 ounce, 1/5 ounce, 4/5 ounce

Suppose a data set consisting of exam scores has a lower quartile QL = 60, a median QM = 75, and an upper quartile QU = 85. The scores on the exam range from 18 to 100. Without having the actual scores available to you, construct as much of the box plot as possible.

Jamming attacks on wireless networks. Refer to the International Journal of Production Economics (Vol. 172, 2016) study of U.S. military jamming attacks on wireless networks used by terrorists, Exercise 1.16 (p. 50). Recall that 80 recent jamming attacks were classified according to network type (WLAN, WSN, or AHN) attacked and number of channels (single- or multi-channel) of the network. The results are summarized in the accompanying table.

Network Type/
Number of Channels

Number of
Jamming Attacks

WLAN / Single

31

WSN / Single

13

AHN / Single

8

WLAN / Multi

14

WSN / Multi

9

AHN / Multi

5

Total

80

a. Construct a Pareto diagram for the data. Interpret the results.

b. Construct a pie chart for network type only. Interpret the results.

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