General

Question 1

The definition of resolution

Answer 1

Ability to see two objects as separate to see in more detail

Question 2

accuracy

Answer 2

a measurement result is considered accurate if it is judged to be close to the true/acceptable value, Random and systematic errors reduce accuracy.

Question 3

precision

Answer 3

a quality denoting the closeness of agreement between measured values obtained by repeated measurements. Reducing the effect of random errors improves precision. A systematic error does not affect precision, as it is the same error each time

Question 4

Random error versus systematic error

Answer 4

random errors: error in a measurement due to small uncontrollable effects, We can’t correct random errors, but we can reduce their effect by making more measurements and calculating the mean.
systematic error: Methods or equipment may introduce systematic errors, producing consistent errors in results

Question 5

Repeatability versus reproducibility

Answer 5

Repeatability: A measurement is repeatable when repetition under the same conditions gives similar results.
Reproducibility: A measurement is reproducible when similar results are produced by different groups or different equipment or altered methods. Reproducibility makes an experiment more valid

Question 6

validity

Answer 6

suitability of the method used to answer the question being asked, To ensure/improve validity, identify control variables and keep them constant to avoid affecting the dependent variables, have a control test, have closer intervals of dependant variables

Question 7

How to tackle a six marker on a pag

Answer 7

• Include variables - independent dependent control x3
• nclude control tests and why
• State how many repeats and state that it’s to identify anomalies
• State how you’re going to record the data, e.g. on a table and draw a graph
• Then do you need to do stats test?

Question 8

how to reduce the percentage error in their
measurements

Answer 8

use (named) equipment with high(er) resolution / AW 
use volumetric flask, instead of measuring cylinder / to
measure the water 
use graduated pipette, instead of dropping pipette / to
measure the glucose solution 
use one dilution instead of two 
produce one 0.01 mol dm-3 solution for all the
populations instead of separate solutions 

Question 9

Why is standard deviation better than range for measuring dispersion of data?

Answer 9

It shows the range around the mean instead of total, so it is less affected by the anomaly

Question 10

how to increase confidence in results

Answer 10

D increase number of plants in each group E facilitates identification of anomalies E increases accuracy of the mean E allows assessment of repeatability / precision D calculate mean E more representative of treatment D calculate range / standard deviation E add bars to graph E measures variability of results E standard deviation less affected by anomalous results D perform statistical test / (unpaired) Students t-test E assess significance of difference E because comparing 2 means