Assessing Primary and Secondary Sources¶
Students identify trends, patterns and relationships; recognise error, uncertainty and limitations in data; and interpret scientific and media texts. They evaluate the relevance, accuracy, validity and reliability of the primary or secondary-sourced data in relation to investigations.
Note
The definitions of accuracy, reliability, and validity are taken from Resources for science instruction (NSW Education)
Primary Sources¶
Accuracy¶
The extent to which a measured value agrees with the true value. Requires prior knowledge about the value to be measured.
An experiment which is accurate should show a value that is close to the true value.
Reliability¶
The extent to which the findings of repeated experiments, conducted under identical or similar conditions, agree with each other. Repeating the experiment minimises the effect of outliers, etc.
Validity¶
The extent to which an experiment addresses the question under investigation. Requires the experiment to be reliable, accurate, and precise. In addition, you must be only changing ONE independent variable, and controlling all the other variables. It must also be using the correct equipment, and addressing the aim. Validity can be assesed with:
mention variables being controlled
only ONE variable should be changed, and its effect on ONE dependent variable
state how errors (e.g. friction in a pendulum swing gravity experiment) have been minimised (or not)
Precision¶
Note
This is not part of the chemistry syllabus. However, it is important to know this as it is a distinct category to accuracy or reliability.
The extent to which multiple measurements, made under identical or similar conditions, agree with each other (i.e. variations within a dataset).
This is referring to the uncertainty of measurements, i.e. how close the measured the value is to the value being measured. Can be quantified with the range of values, written as: \(5\pm1\).
Note
See Mainpulating Uncertainties in Resources for science instruction (NSW Education) for how to combine uncertainties.
Secondary Sources¶
Reliability¶
The consistency of information between sources. Can be evaluated through showing that various sources all gave the same information.
Validity¶
The appropriateness of the information. Needs to consider:
the author’s credentials (are they qualified in that field)
the purpose of the article - is it biased?
is it current (not outdated - this is not “recent”)
is the publisher reputable?
Accuracy¶
The information needs to be both valid and reliable.