ePortfolio Assignment # 3

Statistics and Critical Thinking

(for the ‘Classes and Project’ section of ePortfolio)

Direction: Please type your responses in MSWord using font size 12, double space.

1.  A newspaper report claims that bus stops cause crime because a study showed that crime rates are higher in cities with bus stops than in the rural areas that have no bus stops. What is wrong with that claim?

2.  A New York Times editorial criticized a chart caption that described a dental rinse as one that “reduces plaque on teeth by over 300%.” What is wrong with that statement?

3.  A researcher was once criticized for falsifying data. Among his data were figures obtained from 6 groups of mice, with 20 individual mice in each group. These values were given for the percentage of success in each group. 53%, 58%, 63%, 46%, 48%, 67%. How can we say these data are made up numbers and not real values from the experiment? Explain.

4.  Identify Variable, determine if the data generated is qualitative, discrete or continuous and, list some possible values of the variable for the following cases.

a.  A sample of students is selected and the average amount of time waiting in line to buy textbooks is computed.

Variable: ______

Data is: Qualitative Discrete Continuous

List three possible values of the variable: ______

b.  Nielson Media Research surveys 5000 randomly selected households to find what different TV channels are popular.

Variable: ______

Data is: Qualitative Discrete Continuous

List three possible values of the variable: ______

5.  Following table gives the relative frequency distribution of Body Mass Index of 40 women.

Body Mass Index / Relative frequency
15.0 – 20.9 / 0.25
21.0 – 26.9 / 0.40
27.0 – 32.9
33.0 – 38.9 / 0.05
39.0 – 44.9 / 0.05

Give values for the following:

a.  The class width. ______

b.  The lower class boundary of the third class. ______

c.  The upper class boundaries of the first class. ______

d.  The lower class limit of the last class. ______

e.  The Sample size. ______

f.  The frequency of the second class. ______

g.  The missing relative frequency for the third class. ______

h.  The mid point of the fourth class. ______

i.  Percentage of women with Body Mass Index at most 26.9. ______