Topic 11: Part 1 - Measurement/Data Processing

Question 1

What is qualitative data?

Answer 1

Non-numerical information obtained from observations. Eg. colour changes, bubbling.

Question 2

What is quantitative data?

Answer 2

Information obtained from measurements and associated with random errors/uncertainties.

Question 3

What is the uncertainty of an analogue scale?

Answer 3

Half of the smallest division.

Question 4

What is the uncertainty of a digital scale?

Answer 4

The smallest scale division. Eg. 1.068 would be 1.068±0.001

Question 5

What are random errors?

Answer 5

Errors of precision. Can be minimised by repeated measurements.

Question 6

What are random errors caused by?

Answer 6

• Changes in the environment eg. temperature
• The observer misinterpreting the reading
• Insufficient data
• The readability of the measuring instrument

Question 7

What are systematic errors?

Answer 7

Errors of procedure (to do with accuracy). These can be reduced by careful experiment design.

Question 8

What are systematic errors caused by?

Answer 8

• Consistently measuring from the top instead of the bottom of the meniscus
• Overshooting volume of a liquid

Question 9

Define accuracy.

Answer 9

How similar the results are to the expected.

Question 10

Define precision.

Answer 10

How similar the results are to each other.

Question 11

How do we calculate uncertainties with addition and subtraction?

Answer 11

By adding the uncertainties. Use the half range rule.

Question 12

How do we calculate uncertainties when multiplying or dividing? (+ significant figures rule)

Answer 12

The sum of the individual percentage uncertainties. The answer is quoted to the same number of significant figures as the least precise data.