extended biology

Question 1

Accuracy

Answer 1

A measure of the closeness of an individual test result to the true value

Question 2

Precision

Answer 2

The closeness of agreement between repeated measurements. Precise results may not be accurate

Question 2

Resolution

Answer 2

The smallest change in a measured quantity that an instrument can detect.

Question 2

Anomaly

Answer 2

A result that does not fit the trend and is different from other repeats.

Question 2

Repeatability

Answer 2

The precision obtained when results are produced over a short timescale by one person using the same equipment.

Question 3

Reproducibility

Answer 3

The precision obtained when results are produced by different people using equivalent equipment over a wider timescale

Question 4

Uncertainty

Answer 4

The range within which the true value is expected to lie, often taken as half a division on either side of the smallest unit on the scale

Question 5

Calculating uncertainty

Answer 5

PercentageUncertainty=(uncertainty/quantity measured)
×100
Example: If 50 cm³ of HCl is measured with an uncertainty of ±0.05 cm³, the percentage uncertainty is:

(0.05/50)×100=0.1%

Question 6

Random errors

Answer 6

Errors due to experimenter judgment that can be reduced by repeating the procedure

Question 7

Systematic errors

Answer 7

Errors inherent in equipment that are repeated with every measurement. They can be accounted for if the percentage error is known

Question 8

validity

Answer 8

A measurement is valid if it measures what it is supposed to. Validity can be improved by controlling variables, refining techniques, and reducing bias

Question 9

percentage change

Answer 9

%change = ( new value - original value/original value) x100
Used for comparisons when different start values are used in experiments