Estadistica

Chapter 2
Descriptive Statistics: Tabular and Graphical Presentations




Learning Objectives


1. Learn how to construct and interpret summarization procedures for qualitative data such as : frequency and relative frequency distributions, bar graphs and pie charts.


2. Learn how to construct and interpret tabular summarization procedures for quantitative data suchas:
frequency and relative frequency distributions, cumulative frequency and cumulative relative frequency distributions.


3. Learn how to construct a dot plot, a histogram, and an ogive as graphical summaries of quantitative data.


4. Learn how the shape of a data distribution is revealed by a histogram. Learn how to recognize when a data distribution is negativelyskewed, symmetric, and positively skewed.


5. Be able to use and interpret the exploratory data analysis technique of a stem-and-leaf display.


6. Learn how to construct and interpret cross tabulations and scatter diagrams of bivariate data.
Solutions:


1.
|Class |Frequency |Relative Frequency |
|A |60|60/120 = 0.50 |
|B | 24 |24/120 = 0.20 |
|C | 36 |36/120 = 0.30 |
| |120 | 1.00 |




2. a. 1 - (.22 + .18 + .40) = .20


b. .20(200) = 40


c/d.
|Class|Frequency |Percent Frequency |
|A |.22(200) = 44 | 22 |
|B |.18(200) = 36 | 18 |
|C |.40(200) = 80 | 40 |
|D |.20(200) = 40 | 20 |
|Total |200 |100|




3. a. 360° x 58/120 = 174°


b. 360° x 42/120 = 126°


c.
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d.
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4. a. The data are qualitative.


b.
| | |Percent Frequency |
|Newspaper |Frequency | |
|Liberty Times |24|48 |
|China Times |15 |30 |
|United Daily News |7 |14 |
|Apple Daily |4 |8 |
|Total: |50 |100 |c.
[pic]
[pic]
d. Liberty Times has the largest market share. China Times is second.


5. a.
|Name |Frequency |Relative Frequency |Percent Frequency |
|Chan |10 |.200 |20.0% |
|Chang |7 |.140 |14.0%|
|Lee |8 |.160 |16.0% |
|Liu |7 |.140 |14.0% |
|Wang |12 |.240 |24.0% |
|Young |6 |.120 |12.0% |
||50 |1.000 |100.0% |









b.
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c. Chan .200 x 360 = 72.0(
Chang .140 x 360 = 50.4(
Lee .160 x 360 = 58.6(
Liu .140 x 360 = 50.4(
Wang .240 x 360 = 86.4(
Young .120 x 360 = 43.2(


[pic]


d. Most common: Wang, Chan, and Lee


6. a.
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