COMMENTARY


FIGURE 1


OBJECT IN MOTION


If Bert and Ernie were pushing a box at the same time, how could you tell who was pushing harder? If they were on adjacent sides of the box, as shown in the middle example, it would be easy to tell how hard each one was pushing. (Graphic by USAASC)


FIGURE 2


REDUCING UNCERTAINTY


The plot on the left shows the results of a well-designed experiment. In the example on the right, the two results have considerable uncertainty. While the squares are in similar places in both examples, the possible range is much larger on the right. These ranges represent the uncertainty about how far Bert and Ernie push the box on average. (Graphic by USAASC)


To see the consequences of incorrectly changing the test, it is useful to look at the results of data analysis. Often the most informative way to analyze data is with some kind of statistical analysis. Regression analysis of the Bert and Ernie experiment created the two plots in Figure 2.


The plots show the results of analysis for two exper- iments. The plot on the left is from analysis of a well-designed experiment and on the right from a poorly designed experiment. The black dots represent the esti- mated or most likely value of the average distance that Bert and Ernie push the box. Notice that the black dots


continued on page 90


https://asc.ar my.mil


89


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124