DFW rates. One measure of student success for colleges and universities is the percent of admitted students who graduate. Studies indicate that a key issue in retaining students is their performance in so-called gateway courses. These are courses that serve as prerequisites for other key courses that are essential for student success. One measure of student performance in these courses is the DFW rate, the percent of students who receive grades of D, F, or W (withdraw). A major project was undertaken to improve the DFW rate in a gateway course at a large midwestern university. The course curriculum was revised to make it more relevant to the majors of the students taking the course, a small group of excellent teachers taught the course, technology (including clickers and online homework) was introduced, and student support outside the classroom was increased. The following table gives data on the DFW rates for the course over three years.17 In Year 1, the traditional course was given; in Year 2, a few changes were introduced; and in Year 3, the course was substantially revised. Year DFW rate Number of students taking course Year 1 42.3% 2408 Year 2 24.9% 2325 Year 3 19.9% 2126 Do you think that the changes in this gateway course had an impact on the DFW rate? Write a report giving your answer to this question. Support your answer by an analysis of the data.

Parameter Population Proportion, a fixed quantity. Population Proportion = p Sample Proportion = p hat (estimate) number of successes over the sample size Will modify from each sample Only estimate of parameter Sampling Distribution of Statistics Values of the figure from all potential sample size Describing quantitative number Center mean of all values of the parameter Spread increasing of sample size means the spread is decreasing Shape sample size increases the graph looks more as a bellshaped Caveats Must have a symbolic tester N must be “big enough” Normal Distribution Draw curve and axis Area that signifies probability