PSYC 2021 - Statistical Methods I Lab Exercise 2: Central Tendency and Variability Use R to solve the following problems, and for practice you can also solve some or all of the questions by hand. 1. Below are the posttraumatic stress scores of 15 soldiers who served in Ukraine PTS: 45, 32, 24, 67, 74, 56, 82, 22, 22, 65, 66, 35, 17, 34, 52 a) calculate the mode, median, mean and 20% trimmed mean of PTS scores b) calculate the range, interquartile range, mean absolute deviation, median absolute deviation, variance and standard deviation of PTS scores (note: if it is not specified, we are always talking about the estimated population variance, not the population variance or biased sample variance) 2. Recalculate the median and the variance, but this time do not use the built in functions in R (i.e., calculate the median without 'median()' and the variance without 'var() 3. Produce an overall summary (mean, median, variance, etc.) of the PTS variable using the describe function from the psych package. Did you obtain the same trimmed mean value as that you calculated in 1(a)? If not, why