Question

Creating and interpreting a Normal Quantile-Quantile (Normal Q-Q) plot.

The data you will be using is the distance in miles from home to campus for statistics students.

150      30        105      88        94        15        55        122      45        67        18        126      30

143      98        15        30        62        111      87        38        20        34        39        46        14

144      23        94        44        97        65        120      123      99        45        57        209      20

133      72

1. Column 1: Sort the data values from least to greatest. Use the Sort and Filter feature on the Home tab. (You could title Column 1 “Data Values”)
2. Column 2: Number the data values, i, from 1 to n. We are using n to represent the total number of data values (the sample size). (You could title Column 2 “i”)
3. Column 3: Calculate the probability using the formula = i/(n+1) (Remember i draws from Column 2)
4. Column 4: Find the Standard Normal Z-scores for probabilities from Column 3. Use Excel function NORM.S.INV. You can find this function using the Formula tab . . . More Functions . . . Statistical . . . NORM.S.INV (probability from column 3).
5. Create a scatterplot where the x-axis values are the Z-scores (Column 4) and the y-axis values are the Data values (Column 1). Label the x- and y-axes.
6. Based on the graph and the information from the video, determine if the data is normal. Using a textbox, explain the reasoning behind your answer.

Answer 1

1.980752397 0 1.668391194 1.465233793 1.309171717 -1.179761118 1.067570524 0.967421566 0.876142849 -0.791638608 0.712443032 0.637484161 0.565948822 0.497200571 0.430727299 0.366106357 0.302980448 0.241040394 0.18001237 0.119648113 -0.0597171 1.39214E-16 5 0.119048 6 0.142857 7 0.166667 8 0.190476 10 0.238095 11 0.261905 12 0.285714 13 0.309524 14 0.333333 15 0.357143 16 0.380952 18 0.428571 19 0.452381 20 0.47619 220.52381 23 0.547619 24 0.571429 25 0.595238 26 0.619048 0.119648113 0.18001237 0.241040394 0.302980448 0.366106357 0.430727299 0.497200571 0.565948822 0.637484161 0.712443032 0.791638608 0.876142849 0.967421566 1.067570524 1.179761118 1.309171717 1.465233793 1.668391194 1.980752397 28 0.666667 29 0.690476 0 0.714286 31 0.738095 2 0.761905 33 0.785714 35 0.833333 37 0.880952 39 0.928571 40 0.952381 0

1.2 0.4 -0.4 -2 14 53 92 131 170 209