ch1: scientific investigation

Question 1

true value

Answer 1

the value that would be found if the quantity could be measured perfectly.

Question 2

accuracy

Answer 2

how close the measured value is to the true value

Question 3

precision

Answer 3

how close two or more measurements are to each other. it is a measure of repeatability/reproducibility. precision, however, gives no indication of how close the measurements are to the true value, only how close they are to each other.

Question 4

measurement result

Answer 4

the final result, usually the avg of several measurement values. if only one value is measured, then the measurement result is that one value.

Question 5

repeatability

Answer 5

how closely successive measurements agree with each other when they’re the same quantity being measured and carried out under the same conditions of measurement, such as the same measuring instrument and the same location.

Question 6

reproducibility

Answer 6

how closely the quantity being measured and the results of measurement agree when the conditions of measurement are changed. examples of changed conditions include a different observer, different measuring instruments or different locations.

Question 7

validity

Answer 7

a valid experiment is one that investigates what it claims to investigate. experimental design and implementation should be considered when evaluating validity. for example, if controlled variables are changed or if there is observer bias, then the experiment is not valid.

Question 8

random errors

Answer 8

• affects the precision of measurement
• may be present in all measurements
• unpredictable variations in the measurement process that results in a spread of readings

Question 9

systematic errors

Answer 9

• causes readings to differ from the true value in a systematic manner
• when the same value is measured repeatedly, the error will be the same
• systematic errors result from incorrect calibration of equipment, inappropriate methods or instrumentation limitations

Question 10

repeated measurements

Answer 10

used to reduce the effect of random errors and the likelihood of mistakes.

Question 11

mistakes

Answer 11

• should not be included in reporting and analysis
• experiment should be repeated correctly

Question 12

uncertainty

Answer 12

uncertainty is the margin for error in a measurement.

Question 13

addition & subtraction sig fig rules

Answer 13

in addition and subtraction, you round the answer to whichever number had the least amount of sigfigs

Question 14

outlier

Answer 14

• data pts/observations that differ significantly from other data points or observations
• should be further analysed and accounted for
• repeated experiments are good for examining outliers