In: Statistics and Probability
(b) Determine the proportion of the Revenue Growth data that lies within 1, 2, and 3 standard deviations of the mean. Determine, using the empirical rule, if the Revenue Growth data is approximately normally distributed.
| Company Name | Revenue Growth | 
| (% in last year) | |
| Abercrombie & Fitch Co. | 2.7 | 
| American Eagle Outfitters | 2.5 | 
| bebe stores, inc. | 10.0 | 
| Birks Group Inc | 5.3 | 
| BJs Wholesale Club Holdings Inc | 3.4 | 
| Boot Barn Holdings Inc | 12.7 | 
| Bravada International Ltd. | -4.7 | 
| Buckle Inc | -14.9 | 
| Burlington Stores Inc | -13.5 | 
| Cache Inc | -9.9 | 
| Caleres Inc | -10.8 | 
| Cato Corp | 9.2 | 
| Chico's FAS, Inc. | 10.4 | 
| Childrens Place Inc | -16.0 | 
| Christopher & Banks Corporation | 8.9 | 
| Citi Trends, Inc. | -9.9 | 
| Companhia Brasileira de Distribuicao | 25.7 | 
| Costco Wholesale Corporation | 1.6 | 
| Designer Brands Inc | -0.2 | 
| Destination Maternity Corp | -15.1 | 
| Dillard's, Inc. | -2.4 | 
| Express, Inc. | -9.9 | 
| Foot Locker, Inc. | -0.9 | 
| Francesca's Holdings Corp | 24.8 | 
| Gap Inc | 2.4 | 
| Genesco Inc. | -3.3 | 
| Guess?, Inc. | -4.5 | 
| J C Penney Company Inc | -4.5 | 
| J.Jill Inc | -5.4 | 
| Kohl's Corporation | 4.4 | 
| L Brands Inc | 8.7 | 
| Macy's Inc | -8.7 | 
| Nordstrom, Inc. | -5.2 | 
| PriceSmart, Inc. | 0.4 | 
| Qingco Inc | -35.8 | 
| Ross Stores, Inc. | 2.6 | 
| RTW Retailwinds Inc | 0.1 | 
| Sears Holdings Corp | -0.5 | 
| Shoe Carnival, Inc. | 8.8 | 
| Stage Stores Inc | 52.4 | 
| Stein Mart, Inc. | 3.7 | 
| Tailored Brands Inc | -4.3 | 
| Tandy Leather Factory, Inc. | -9.9 | 
| Tilly's Inc | 7.2 | 
| TJX Companies Inc | 3.3 | 
| Urban Outfitters, Inc. | 0.8 | 
| Walmart Inc | -3.5 | 
| Zumiez Inc. | -8.1 | 
There are 48 data points
by 68-95-99.7 rule,
68% lies within 1 sd, 95% lies within 2 sd , and 99.7 % lies within 3 sd of mean
using given data
| Company Name | Revenue Growth | ||||
| (% in last year) | z-score | |z| < 1 | |z| < 2 | |z| < 3 | |
| Abercrombie & Fitch Co. | 2.7 | 0.19 | 1 | 1 | 1 | 
| American Eagle Outfitters | 2.5 | 0.18 | 1 | 1 | 1 | 
| bebe stores, inc. | 10 | 0.76 | 1 | 1 | 1 | 
| Birks Group Inc | 5.3 | 0.39 | 1 | 1 | 1 | 
| BJs Wholesale Club Holdings Inc | 3.4 | 0.25 | 1 | 1 | 1 | 
| Boot Barn Holdings Inc | 12.7 | 0.97 | 1 | 1 | 1 | 
| Bravada International Ltd. | -4.7 | -0.38 | 1 | 1 | 1 | 
| Buckle Inc | -14.9 | -1.17 | 0 | 1 | 1 | 
| Burlington Stores Inc | -13.5 | -1.06 | 0 | 1 | 1 | 
| Cache Inc | -9.9 | -0.78 | 1 | 1 | 1 | 
| Caleres Inc | -10.8 | -0.85 | 1 | 1 | 1 | 
| Cato Corp | 9.2 | 0.70 | 1 | 1 | 1 | 
| Chico's FAS, Inc. | 10.4 | 0.79 | 1 | 1 | 1 | 
| Childrens Place Inc | -16 | -1.25 | 0 | 1 | 1 | 
| Christopher & Banks Corporation | 8.9 | 0.67 | 1 | 1 | 1 | 
| Citi Trends, Inc. | -9.9 | -0.78 | 1 | 1 | 1 | 
| Companhia Brasileira de Distribuicao | 25.7 | 1.97 | 0 | 1 | 1 | 
| Costco Wholesale Corporation | 1.6 | 0.11 | 1 | 1 | 1 | 
| Designer Brands Inc | -0.2 | -0.03 | 1 | 1 | 1 | 
| Destination Maternity Corp | -15.1 | -1.18 | 0 | 1 | 1 | 
| Dillard's, Inc. | -2.4 | -0.20 | 1 | 1 | 1 | 
| Express, Inc. | -9.9 | -0.78 | 1 | 1 | 1 | 
| Foot Locker, Inc. | -0.9 | -0.09 | 1 | 1 | 1 | 
| Francesca's Holdings Corp | 24.8 | 1.90 | 0 | 1 | 1 | 
| Gap Inc | 2.4 | 0.17 | 1 | 1 | 1 | 
| Genesco Inc. | -3.3 | -0.27 | 1 | 1 | 1 | 
| Guess?, Inc. | -4.5 | -0.36 | 1 | 1 | 1 | 
| J C Penney Company Inc | -4.5 | -0.36 | 1 | 1 | 1 | 
| J.Jill Inc | -5.4 | -0.43 | 1 | 1 | 1 | 
| Kohl's Corporation | 4.4 | 0.32 | 1 | 1 | 1 | 
| L Brands Inc | 8.7 | 0.66 | 1 | 1 | 1 | 
| Macy's Inc | -8.7 | -0.69 | 1 | 1 | 1 | 
| Nordstrom, Inc. | -5.2 | -0.42 | 1 | 1 | 1 | 
| PriceSmart, Inc. | 0.4 | 0.01 | 1 | 1 | 1 | 
| Qingco Inc | -35.8 | -2.79 | 0 | 0 | 1 | 
| Ross Stores, Inc. | 2.6 | 0.18 | 1 | 1 | 1 | 
| RTW Retailwinds Inc | 0.1 | -0.01 | 1 | 1 | 1 | 
| Sears Holdings Corp | -0.5 | -0.05 | 1 | 1 | 1 | 
| Shoe Carnival, Inc. | 8.8 | 0.66 | 1 | 1 | 1 | 
| Stage Stores Inc | 52.4 | 4.04 | 0 | 0 | 0 | 
| Stein Mart, Inc. | 3.7 | 0.27 | 1 | 1 | 1 | 
| Tailored Brands Inc | -4.3 | -0.35 | 1 | 1 | 1 | 
| Tandy Leather Factory, Inc. | -9.9 | -0.78 | 1 | 1 | 1 | 
| Tilly's Inc | 7.2 | 0.54 | 1 | 1 | 1 | 
| TJX Companies Inc | 3.3 | 0.24 | 1 | 1 | 1 | 
| Urban Outfitters, Inc. | 0.8 | 0.05 | 1 | 1 | 1 | 
| Walmart Inc | -3.5 | -0.29 | 1 | 1 | 1 | 
| Zumiez Inc. | -8.1 | -0.64 | 1 | 1 | 1 | 
| 0.210416667 | frequency | 40 | 46 | 47 | |
| 12.9299461 | proportion | 0.833 | 0.958 | 0.979 | 
hence 83.3 % lies within 1 sd,
95.8 % within 2 sd
97.9 % within 3 sd
we see that there is high proportion of data within 1 sd
hence the Revenue Growth data is not approximately normally distributed.