# T&P Terminology Flashcards

1
Q
1. Define accuracy.
2. Define error.
A

Accuracy: the closeness of agreement between a measurement and the true value.

Error: the difference between a measurement and the true value.

Accuracy cannot be quantified, whereas error can. True value = that which would have been obtained in an ideal measurement.

2
Q

Define precision.

A

The closeness of agreement between independent measurements obtained under the same conditions.

3
Q

Define uncertainty.

A

The interval within which the true value can be considered to lie with a given level of probability.

4
Q

Give the formula for percentage uncertainty.

A

100 x uncertainty / measurement

5
Q

A measuring instrument has increments of magnitude x. What the uncertainty in a single reading?

A

x/2

6
Q

A burette has 0.1 cm3 increments.

1. What is the uncertainty in each measurement?
2. To how many decimal places should readings be recorded?
A
• 0.05 x 2 = 0.1 cm3
• Two decimal places, the second figure being either 0 or 5

Uncertainty is doubled since you take two readings to get one measurement