experimental design - key terms

locked in 26/11/24

accuracy

how close the experimental result obtained is to the accepted, or ‘true’ value of the quantity

precision

how closely 2 more more measurements agree with each other

true value

the value or range of values that would be found if the quantity could be measured perfectly

reproducibility

the closeness of agreement between independent results obtained with the same method on identical test material but under different conditions (different operators, different apparatus, and/or different labs)

repeatability

the closeness of agreement between independent results obtained with the same method on identical test materials under the same conditions

validity

how well the experimental design matches the requirements of the investigation to produce results that address the stated aim/s

improving the variables will improve validity

uncertainty

source of variation of data, indluding human capacity in measurement, the nature of instrumentation and external factors in the laboratory (e.g. temperature, air currents, e.t.c.)

outliers

an observation or data point that falls outside the range of other data collected. The data point (observation) will be much higher or lower than the other data points.

systematic error

affects the accuracy of a measurement and causes reading to be different from the true value.

Measurements will be in one direction (too high OR to low) from the true value.

This cannot be improved by repeating the measurements or calibrating equipment and stuff.

personal error

mistakes or miscalculations in the process of data collection or analysis

random error

affects the precision of a measurement and will always be present (unless counting).

unpredictable variations in data points (in both directions).

can be improved through repeating measurements, averaging data, or refining methodology/technique.

How to write a conclusion?

the results of the experiment show that… This was caused by … Therefore, the hypothesis was/was not supported because…