Your manager has given you an Excel file that contains the names of the company's 500 employees and has asked you to sample 50 employees from the list. You decide to take your sample as follows. First, you assign a random number to each employee using Excel's random number function Rand(). Because the random number is volatile (it recalculates itself whenever you modify the file), you freeze the random numbers using the Copy-Paste Special-Values feature. You then sort by the random numbers in ascending order. Finally, you take the first 50 sorted employees as your sample. Does this approach constitute a statistical or a nonstatistical sample?