Uncertainties and Data Analysis

Question 1

What is the accuracy of a measurement determined by?

Answer 1

how close it is to its ‘true’ value

Question 2

What is the precision of a measurement determined by?

Answer 2

how many significant figures the measurement is read to

Question 3

What is the reliability of a measurement determined by?

Answer 3

how consistent the value is when repeated

Question 4

What uncertainties is precision related to?

Answer 4

scale reading uncertainties

Question 5

How can you reduce the random uncertainty?

Answer 5

taking more measurements (reliability)

Question 6

Analogue and digital scale reading uncertainties

Answer 6

Analogue: +-1/2 the smallest scale division
Digital: +-1 of the least significant digit in display

Question 7

What measurements do systematic uncertainties affect?

Answer 7

all measurements

Question 8

what are calibration uncertainties an example of?

Answer 8

systematic uncertainties e.g. a timer that runs slowly

Question 9

What is the absolute form of an uncertainty?

Answer 9

The actual value of the uncertainty with units e.g. V=(4.2+-0.1)V

Question 10

What are the 3 forms of an uncertainty?

Answer 10

absolute (1 significant figures), fractional (no units) and percentage

Question 11

when combining uncertainties, when may you discard one?

Answer 11

when it is a third less of the largest uncertainty

Question 12

what are the steps of combining uncertainties in different quantities?

Answer 12

1-convert to percentage/fractional and discard any
2-calculate overall fractional uncertainty