In: Statistics and Probability
2. Summarizing interval data - Frequency distributions and histograms
The Dow Jones Industrial Average (DJIA) is a stock index of 30 of the leading companies in the main industries of the United States. It is the second-oldest continuing U.S. market index (after the Dow Jones Transportation Average).
Companies in the DJIA are classified into 10 industries according to the Industry Classification Benchmark (ICB), a classification system developed by Dow Jones & Company and the FTSE Group. Although the DJIA was originally meant to describe the industrial component of the U.S. market, today the modifier “Industrial” in its name is mainly historical. As Table 1 shows, many of its companies have little to do with heavy industry. Table 1, located in the following DJIA Table dropdown menu, shows the companies’ names, ICB classifications, and market capitalizations.
DJIA Table
Table 1
No. |
Company |
Industry |
Capitalization |
---|---|---|---|
(Billions of dollars) |
|||
1 | International Business Machines Corp. | Technology | 129.9 |
2 | Chevron Corp. | Oil and Gas | 86.1 |
3 | Exxon Mobil Corp. | Oil and Gas | 81.5 |
4 | Caterpillar Inc. | Industrials | 70.9 |
5 | 3M Co. | Industrials | 68.9 |
6 | Boeing Co. | Industrials | 68.1 |
7 | Johnson & Johnson | Health Care | 67.8 |
8 | United Technologies Corp. | Industrials | 64.1 |
9 | Procter & Gamble Co. | Consumer Goods | 63.7 |
10 | McDonald’s Corp. | Consumer Services | 60.4 |
11 | Wal-Mart Stores Inc. | Consumer Services | 57.9 |
12 | Coca-Cola Co. | Consumer Goods | 50.0 |
13 | E.I. DuPont de Nemours & Co. | Basic Material | 44.2 |
14 | Hewlett-Packard Co. | Technology | 43.4 |
15 | American Express Co. | Financials | 42.2 |
16 | JPMorgan Chase & Co. | Financials | 40.0 |
17 | Merck & Co. Inc. | Health Care | 37.7 |
18 | Verizon Communications Inc. | Telecommunications | 35.5 |
19 | Alcoa Inc. | Basic Material | 33.8 |
20 | AT&T Inc. | Telecommunications | 32.1 |
21 | Walt Disney Co. | Consumer Services | 30.9 |
22 | General Electric Co. | Industrials | 28.0 |
23 | Bank of America Corp. | Financials | 27.5 |
24 | Microsoft Corp. | Technology | 25.9 |
25 | American International Group Inc. | Financials | 25.1 |
26 | Home Depot Inc. | Consumer Services | 23.4 |
27 | Intel Corp. | Technology | 22.1 |
28 | Citigroup Inc. | Financials | 19.4 |
29 | Pfizer Inc. | Health Care | 18.3 |
30 | General Motors Corp. | Consumer Goods | 13.2 |
Total | 1,412.0 |
Table 2 divides the range of the market capitalization of the DJIA companies into six intervals and gives some of their frequencies and relative frequencies. Based on the information provided in Table 1, use the dropdown menus to fill in the rest of Table 2.
Table 2 |
||
---|---|---|
Market Capitalization |
Frequency |
Relative Frequency |
(Billions of dollars) |
||
110 to 130 | 1 | 0.03 |
90 to 110 | 0 | 0.00 |
70 to 90 | 3 | 0.10 |
50 to 70 | ||
30 to 50 | 10 | 0.33 |
10 to 30 | ||
Total | 30 | 1.0 |
On the following graph, create a relative frequency histogram of the companies’ market capitalizations based on the distribution in Table 1 by using the blue rectangles (drag the circle symbols to increase or decrease the size) to draw each individual bar of the histogram. (Hint: Do not place a rectangle when the frequency of the class is zero.)
10305070901101301.000.800.600.400.200RELATIVE FREQUENCYMARKET CAPITALIZATION (Billions of dollars)
The relative frequency distribution of the market capitalizations is .
Solution :
From the table 1, the frequency table is,
Make Capitalization (Billions of dollars ) | Frequency | Relative frequency (Rounded to two decimal places ) |
10 to 30 | 9 | 0.3 = 0.30 |
30 to 50 | 10 | 0.333333 = 0.33 |
50 to 70 | 7 | 0.233333 = 0.23 |
70 to 90 | 3 | 0.1 = 0.10 |
90 to 110 | 0 | 0 |
110 to 130 | 1 | 0.033333 = 0.03 |
Total | 30 | 1 |
Here, the relative frequency can be calculated using the below formula:
Relative frequency = Frequency / Total frequency
From the above table, the frequency values are obtained from the table 1.
Use Excel to construct the histogram :
From the histogram, the relative frequency distribution of the market Capitalizations is Positively skewed.
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