HW1 Question 2-38 (Posted 4/1/99)

Question:
I have a problem with this question.
- parts a and b referes to question 2-10 which in turn referes to question 2-2.
- part c referes and askes you to compare part a and b with 2-4.
questions 2-2 and 2-4 have nothing to do with each other correct?

Response:
You are right -- the 2-38's reference to 2-4 makes little sense. To fix this, you should do the following
1. Replace the reference in 2-4 with a reference to 2-2.
2. When working 2-7, use the data from exercise 2-2 rather than 2-3.

By using the data from 2-2 in working 2-7, you will then have calculated the sample average, median, and mode for that data and can refer to those number in 2-38 part c.

Box Plots

Question:
>Looking for those equations for the upper and lower boundries. Are they in the book, could >not find the equations?

Answer:
The equations are not in the book as equations. The equations are referred to, implicitly, in Figure 2-10.

Using the Computer for HW#1

Question:
Question on the homework #1. For the first few problems of Chapter 2, are these to be done on the computer or can they be hand written?

Answer:
For the larger data sets, I would prefer that the problems be worked with the computer. This is particularly true for the histograms. You can, however, do them by hand.

Homework #1 was graded in the following manner:  Fifty percent of the score was based on the existence of a solution attempt for each assigned problem.  The remaining 50% of the score was based on the correctness of three randomly chosen problems.   In this case, the three problems were 2-8, 2-12, and 2-30.

The overall scores on this first homework assignment were very high.  Of the 119 students who are presently on the class roster (although some may have dropped), ninety-nine students submitted homework assignments.  The 20 students who did not submit homework assignments received scores of 0.  The analysis below was performed with these "0" scores included.  In the case of this homework assignment, the scores of 0 could be interpreted as different from the remaining scores, and thus be removed from the analysis. Would this have made more sense?

Below I have included the frequency and relative frequency table, a histogram of the grades, and the standard Excel descriptive statistics on the grades.  Again, the scores are quite high, and the overall variability quite low.   Notice the difference, in the descriptive statistics, when I removed the scores of 0. 

Overall -- good job on homework #1.

Frequency (and Relative Frequency) Table

Bin	Frequency	Relative Freq	Cumulative %
0	20	0.17	16.95%
5	0	0.00	16.95%
10	0	0.00	16.95%
15	0	0.00	16.95%
20	0	0.00	16.95%
25	0	0.00	16.95%
30	0	0.00	16.95%
35	0	0.00	16.95%
40	0	0.00	16.95%
45	0	0.00	16.95%
50	0	0.00	16.95%
55	1	0.01	17.80%
60	0	0.00	17.80%
65	0	0.00	17.80%
70	0	0.00	17.80%
75	0	0.00	17.80%
80	2	0.02	19.49%
85	4	0.03	22.88%
90	11	0.09	32.20%
95	23	0.19	51.69%
100	57	0.48	100.00%
More	0	0	100.00%

Homework 1 Grade (Scores of 0 Included)
Mean	78.81
Standard Error	3.31
Median	95.00
Mode	100.00
Standard Deviation	36.08
Sample Variance	1302.02
Kurtosis	1.04
Skewness	-1.70
Range	100.00
Minimum	0.00
Maximum	100.00
Sum	9378.18
Count	119.00
Largest(1)	100.00
Smallest(1)	0.00
Confidence Level(95.0%)	6.55

Homework 1 Grades (Scores of 0 Excluded)
Mean	94.73
Standard Error	0.67
Median	96.67
Mode	100.00
Standard Deviation	6.65
Sample Variance	44.18
Kurtosis	17.73
Skewness	-3.36
Range	48.48
Minimum	51.52
Maximum	100.00
Sum	9378.18
Count	99.00
Largest(1)	100.00
Smallest(1)	51.52
Confidence Level(95.0%)	1.33