Uncertainty, Accuracy + Precision

Question 1

How can uncertainty bars be created in a graph, and how can the uncertainty of the gradient be calculated?

Answer 1

Draw a line of best and worst fit to draw the uncertainty bars. Calculate the gradient of the line of best fit and find the difference between this and the gradient of the line of worst fit to find your absolute uncertainty. Divide this by the gradient of the line of best fit for a percentage uncertainty.

Question 2

What is accuracy?

Answer 2

This is how close a measurement is to it’s true value.

Question 3

What is precision?

Answer 3

This is how close repeated values are to each other.

Question 4

What would be accurate but not precise?

Answer 4

Measurements which are close to the true value but are far apart from each other.

Question 5

What would be precise but not accurate?

Answer 5

Measurements which are close together but do not represent the true value.

Question 6

What is an order of magnitude?

Answer 6

This is where estimates are used to the power of ten, such as when the length of a field is estimated, (1000m).