Percent Error (Distance)
📚 What You'll Learn
- Applying percent error concepts to distance predictions
- Finding the absolute value of the difference between predicted and actual distance
- Building a percent error table from actual distance results
- Estimating percent error by comparing difference to benchmark percentages
In this video, I'm being asked to predict how far the vehicle will travel in 14 seconds.
Looking at the equation and the graph, I predict the vehicle will travel 354.6 centimeters when rounded to the nearest tenth.
When I actually ran the vehicle for 14 seconds and measured the distance, I found that the actual distance was 377.1 centimeters.
In this example, my prediction was off by over 30 centimeters.
Is it possible that being off by 30 centimeters is good?
Well, it varies. If I had predicted the vehicle would travel 60 centimeters and it actually went 30 centimeters, that 30 centimeters is a lot greater proportion than say, if I predicted the car would go 300 centimeters, and it actually went 270 centimeters.
In order to determine if a prediction is good, we're going to need to look at it in proportion to the actual results and use something called: percent error.
Percent error is the proportional difference between a prediction and what actually occurs.
I'm going to use this table to help me estimate my error percentage.
In this case, the vehicle traveled for 14 seconds.
I predicted it would go 354.6 centimeters while it actually traveled 377.1 centimeters.
To find the difference, subtract actual distance from the predicted distance, and then take the absolute value.
For this, I'm going to use a calculator.
The absolute value of that is 22 and five tenths.
And now to find the percent error.
Percent error is calculated from the actual results.
So that means if I made one hundred percent error, I would have been off by 377.1 centimeters.
If I know one hundred percent error, I can find 10 percent error by taking one-tenth of that distance.
377.1 divided by 10 equals 37.7 centimeters when rounded to the nearest tenth.
If I know 10 percent I can find five percent error because five is half of 10, 18.9 centimeters.
And I can find one percent error if I know 10 percent error because one percent is one-tenth of that.
So now I can estimate my percent error by comparing these percentages with my difference.
In this example, my percent error is somewhere between five percent and 10 percent.