Hedging in Data Commentaries

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You are a teaching assistant for an introductory biology course with a total enrollment of 150. Exams are usually given in the evening to avoid losing valuable class time. Because some students have evening commitments, a makeup exam is always given. The professor has noticed a big discrepancy between the scores of the last regular exam and those of the makeup exam. Because you administered the last makeup exam, you have been asked to offer an explanation. You have prepared the data in Table 16. Now write a data commentary, either as a formal report or an e-mail message to your professor.

Table 16: A Comparison of the Regular and Makeup Exam

Items	Regular exam	Makeup exam
Average score (out of 100) Time administered Difficulty of questions Number of students Proctor Board examples Room environment	86 Wednesday, 7:00 p.m. average 125 professor yes about 20C	72 Friday, 4:00 p.m. average 25 teaching assistant no (not considered necessary) about 28C

Dear Professor,

I hope this email finds you well. I am writing this email to present the result of my analysis on the discrepancy observed in the two tests based on the above table.

It is clear that there is a big gap between the average scores of the regular exam and the makeup exam. The first thing that I would like to mention is the possibility of the fact that, some of the students who attended the make-up exam were not well-prepared for the regular exam and chances are that they could not get fully prepared in the last two days.

Since you were the proctor of the regular exam, the student have benefited from your help, hints and of course the board examples during the exams, whereas I did not answer to any questions based on regulations.

In the regular exam there were 125 students attending the test whereas in the makeup exam only 25 students were taking the test. I don’t want to accuse anyone of misbehavior during the exam; however, since you were the only proctor of the exam, the high number of students could increase the chance of cheating in the regular exam.

Finally, since the room's temperature was considerably higher in the makeup exam, that might also be a good reason for the less efficient performance of the students.

I hope these reasons would be convincing and justify the discrepancy between the two exams.

Should you have any more questions, please don’t hesitate to contact me.

Best regards,

TA

Discription of Graphs

Time-response of a second-order system

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This graph illustrates the time-response of a second-order system to a unit step input. There is several information in this graph which describes the behaviors and characteristics of the system. The rise time tr, is the time it takes for the response of the system to go from 10% to 90% of its final value. The settling time indicates the time it takes for the response to settle within 2-5% of its steady-state value. The smaller this value is, the faster response the system has to unit step input. Overshoot b, is the height of the first peak. The smaller the overshoot is, the smoother the system behaves. The damping factor of the system fd ,is related to the overshoot ratio and the time it takes for the overshoot to appear in the response (tp). The main characteristics of any system which could be represented by a second-order transfer function, can be explained through this response. This is a general graph which explaines a family of second-order systems. That is why it is described in terms of parameters rather than specific values or numbers.

Northbound Gray Whales Statistics by Week

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Click on the image to enlarge

The above graph is the Northbound gray whales counted by week in spring migration 2010 in Los Angles, California.
As can be seen, the graph approximates a normal distribution of whales migrations during the months of February to May.  As shown in the graph, we have the least counts of whales close to the margins of the count period, i.e. the first week of February and the last week of May. It can be clearly seen that the number of whales migrated, has an increasing trend till the third week of March. The graph has its peak at the third week of March. There is a dip of 60 between the first and third week of March which is an exception to this upward movement. Then passing the peak of the graph in the third week of March, the number of whales migrated will start declining until the end of the report period. There is again an exception between April 12 and April 18 to this trend. 
This increasing and then decreasing trends could be explained by the fact that, as we approach the mid March, the environmental changes in this region are more ideal for the migration of gray whales. So most of the gray whales migrate in this period.

A Condensed Method Section on an Interview by Mei-Lan

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The research has been carried out to determine, whether the prevailing myths: Chinese communities would always look after their elderly, were in fact true. This is an interview- type research. The data were collected from subjects, who were chosen from local Chinese communities, in big cities in the east and west coasts. The subjects were introduced by friends, and friends of friends of the interviewer.

Due to the lack of time and some other constraints, only about ten people were interviewed, which was not enough data for any type of statistical analysis.

A face-to-face interview technique was used, to increase the integrity of the research. Each interview lasted around an hour. A so called "semi-structured" interview was used, that is, not the same amount of questions were asked from all interviewees.

The interviewees were free to speak with any of Mandarin, Taiwanese, or English languages. This is a strong point of this research method, because the interviewees could express themselves more freely.
Overall, an appropriate technique was used in  this interview, however, the low number of interviewees decreased the liability of the research.