Lab Exercise 7

Please upload the knitted .pdf file on Moodle by 23:59.

Suppose that the object x created below is the raw score on a test from 200 examinees.

x <- sample(rep(0:10, times=c(4, 10, 18, 30, 38, 38, 30, 18, 10, 2, 2)))

  1. Construct a frequency table containing three columns: Scores, Frequency, and Cumulative frequency.

  2. Calculate the percentiles corresponding to scores from 0 to 10. 0 and 10 are the minimum and the maximum values of the raw scores.

  3. Obtain the T-scores of all 200 examinees and draw a histogram of the T-scores.

hint: First, we need to obtain the percentile scores for all examinees.

  1. Obtain the stanines of all 200 examinees and check the freqeuncy of each stanine score.

  2. Construct a data.frame that contains 4 columns: raw scores, percentiles, T-scores, and stanines for the 200 examinees.