experimental skills Flashcards
1
Q
accuracy
A
how close it is to the ‘true’ value of the quantity being measured
2
Q
precision
A
- refers to how closely a set of measurement values agree with each other
- gives no indication of how close the measurements are to the true value
- a separate consideration to accuracy
3
Q
repeatability
A
- the closeness of the agreement between the results of successive measurements of the same quantity being measured,carried out under the same conditions of measurement
- These conditions include the same measurement procedure, the same observer, the same measuring instrument used under the same conditions, the same location, and repetition over a short period of time.
- you repeating the experiment
4
Q
reproducibility
A
- the closeness of the agreement between the results of measurements of the same quantity being measured, carried out under changed conditions of measurement.
- These different conditions include a different method of measurement, different observer, different measuring instrument, different location, different conditions of use, and different time.
- a different person reproducing your results
5
Q
true value
A
the value, or range of values, that would be found if the quantity could be measured perfectly.
6
Q
validity
A
- a measurement is said to be valid if it measures what it is supposed to be measuring
- An experiment is said to be valid if it investigates what it sets out and/or claims to investigate.
7
Q
personal errors
A
include mistakes or miscalculations
8
Q
random errors
A
- affect the precision of a measurement and are present in all measurements except for measurements involving counting.
- Random errors are unpredictable variations in the measurement process and result in a spread of readings.
- The effect of random errors can be reduced by making more or repeated measurements and calculating a new mean and/or by refining the measurement method or technique.
9
Q
systematic errors
A
- affect the accuracy of a measurement.
- Systematic errors cause readings to differ from the true value by a consistent amount each time a measurement is made, so that all the readings are shifted in one direction from the true value.
- The accuracy of measurements subject to systematic errors cannot be improved by repeating those measurements.
10
Q
uncertainty
A
- the uncertainty of the result of a measurement reflects the lack of exact knowledge of the value of the quantity being measured.
- VCE Biology requires only a qualitative treatment of uncertainty. When evaluating personally sourced or provided data, students should be able to identify contradictory, provisional and incomplete data including possible sources of bias.
- it IS NOT errors
11
Q
outliers
A
- Readings that lie a long way from other results are sometimes called outliers.
- Repeating readings may be useful in further examining an outlier.
12
Q
hypothesis
A
- A hypothesis is a statement that can be tested.
- It must be a prediction.
- It must be testable.
- It must link directly to your results.
- if… then…
13
Q
IV and DV
A
- A variable is simply a ‘thing that changes’.
- An experiment needs variables, or it’s not an experiment
- The independent variable is not dependent on the results. It is the thing you change to set up the experiment.
- The dependent variable is measured. It is the results. It is the thing that the experiment changes.
14
Q
controls
A
- A control is designed to eliminate extraneous variables.
- A control should replicate the entire testing procedure excluding the independent variable
- used to compare the effect of the independent variable
15
Q
benefits of larger sample size
A
- minimises impact of random errors
- increases accuracy of the results
