CSCI A113
Assignment Four

First semester 2000-2001

Due date
At the end of lab 10 (November 30-December 1).
Late policy
No late policy. You need to turn this on time.
Work policy
Working in groups is accepted but you need to turn in your own version of the assignment.
Task
Start by downloading the data from the midterm exam.

Then review chapter 3 in your textbook (thin green book) and especially section 3.5 (pp. 40-47).

The aim of this data analysis is to assess student learning on the midterm examination. The data analysis sequence should begin by developing a graphical presentation of the results and then by computing certain statistical measures, as detailed below. Data for this example comes from our midterm examination 10 days ago. There were 28 questions with each question counting a certain number of points. The total number of points was 77. There was one student that obtained a perfect score (line 49 in the spreadsheet) so you can use that line for the max number of points per question on the exam.

Scores include partial credit for each question. Do the following:

  1. (5 points) Compute total score for each student and express it in terms of percents.

  2. (10 points) Sort the students score in ascending order and chart the results using a bar chart.

  3. (30 points) Compute the descriptive statistics using Excel's Tool-Pak to include:

    • the mean score
    • the range
    • the median
    • the variance
    • the standard deviation
    • Pearson's coefficient of skewness

The next set of procedures is aimed at extracting information of student performance relative to individual questions.

  1. (10 points) Compute the item difficulty for each question, as follows:

    1. start by computing the mean number of points per question
    2. divide by the total number of points per question to obtain a percentage

    This percentage will give you a measure of difficulty (between 0 and 1) for each item. The higher the value the easier the item: a value of 1 means everybody got maximum number of points on the problem (so the problem was tremendously easy). A value of 0 means nobody solved any part of that problem (which means the problem was extremely hard). This value is also equal to "the percentage of students who got the question right".

  2. (10 points) Sort the item dificulties in ascending order and develop a histogram of correct answers in bins of 5 as well as bins of 2.

  3. (30 points) Compute the descriptive statistics for the performance set:

    1. mean
    2. mode
    3. median
    4. range
    5. variance
    6. standard deviation
    7. skewness

  4. (5 points) Based on the entire analysis was the exam hard, moderate, or easy? Justify your answer.
Grading
The AI will provide you with feedback in one week. Grades will be posted on-line.

Last updated: November 26, 2000 by Adrian German for A113