This question is about Fitts' Law - Speed Accuracy Trade-off

The chart below shows the results of how changing the difficulty of the movement (and therefore the accuracy requirements) affects the speed of movement (as determined by the movement time).

My question: In the context of Fitts' Law, explain what is meant by the term speed-accuracy trade-off? Explain your answer in terms of movement time (MT), the index of difficulty (ID), movement amplitude (A), and target width (W)?

Here are some formulas relate to this question:ID = log2(2A/W),MT = a + b(ID),MT = a + b[log2(2A/W)]

Here is the formula for the chart below: MT = 76.061 +105.91_ [log2(2A/W)]

G Movement Amplitude (A) Target Width (W) Index of Difficulty (ID) Movement Time (MT) 215 IN 239 291 354 Co CO + IN 426 520 Fitt's Law 600 y = 105.91x + 76.061 520 R2 = 0.9044 500 426 400 354 Movement Time (Msec) 291 BOO 239 215 200 100 33 34 35 36 37 0.5 15 2.5 B.5 45 38 39 40 Index of difficulty (bits)