General vocab

Question 1

Resolution

Answer 1

The smallest change in quantity that can be measured with the apparatus you are using. Refers both to the apparatus used to measure out quantities as part of the procedure and the apparatus used to collect results. It refers to the number of significant figures/ decimal places in readings.

Question 2

Precision

Answer 2

a measure of the closeness of agreement between individual results obtained using the same procedure under exactly the same conditions.

However, closeness of replicates does not mean that the data are close to the true value.

Question 3

Repeatable results

Answer 3

Replicate results that are in close agreement. You can use mathematical methods to help evaluate the variation in replicate results.

Question 4

Reproducible results

Answer 4

Results that are produced by someone else who follows exactly the same procedure using the same apparatus and materials, but inn a different place and at a different time. You can only comment o this I response to a question if you are given results from different people.

Question 5

Accuracy

Answer 5

a measure of the closeness of agreement between individual results or a set of results and an accepted ‘true’ value. Errors and limitations reduce the chances that results are close to the ‘true’ value and therefore accurate.

Question 6

Systematic errors

Answer 6

Always the same throughout the investigation. A common type of systematic error is when the measuring device gives readings that are incorrect by a certain value. It could be that one of the controlled variables is always incorrect by the same quantity, If there are small systematic errors (that are always the same) then the data may be precise, but not accurate. The effect of these errors is to overestimate or underestimate the true values of the dependent variable.

Question 7

Random errors

Answer 7

occur when you do not carry out the procedure I exactly the same way each time. You may also read the apparatus in a slightly different way each time you take a reading. These errors affect some of the results, but not all of them. They do not always affect the results in the same way. Random errors could be the result of the variation in biological material.

Question 8

Anomalous results

Answer 8

Results that do not fit the trend. An anomalous result can be:

• A replicate result that differs significantly from the others
• A result (which may or may not be a mean) for one value of the independent variable that does not fit the overall trend and is not included in the curve of best fit.

The anomaly could be the first result taken before he experimenter was confident inn he procedure.

Question 9

VALIDITY

Answer 9

refers to individual measurements and to the whole procedure.

A good method generates VALID results.
A valid method is one that answers the stated hypothesis.

Validity refers to individual measurements and to the whole procedure.

If commenting on the confidence in a conclusion, consider:

• the LIMITATIONS in na procedure
• any uncontrollable variables
• the effects of errors (systematic and random) on the results.
• the repeatability (reliability) of the results
• the precision of the data collected.
• the accuracy of the results.

(give positive aspects first, followed by some criticism. Refer to specific aspects of the procedure and results)

Question 10

Uncertainty

Answer 10

half the smallest graduation on the apparatus.

e.g., if the smallest division on a syringe is 1.0 cm cubed, the uncertainty is +/-0.5cm cubed.