Flashcards in AQA Key Terms Deck (62)
A measurement result is considered accurate if it is judged to be close to the true value.
Marking a scale on a measuring instrument
Information, either qualitative or quantitative, that has been collected
Define measurement error
The difference between a measured value and the true value
These are values in a set of results which are judged not to be part of the variation caused by random uncertainty
Define random error
Errors that cause readings to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next
When are random errors present?
Random errors are present when any measurement is made, and cannot be corrected
How can you reduce the effect of random errors?
The effect of random errors can be reduced by making more measurements and calculating a new mean
Define systematic error
Errors that cause readings to differ from the true value by a consistent amount each time a measurement is made
What are sources of systematic errors?
Sources of systematic error can include the environment, methods of observation or instruments used
Can systematic errors be dealt with via repeats?
What should be done if a systematic error is suspected?
If a systematic error is suspected, the data collection should be repeated using a different technique or a different set of equipment, and the results compared.
Define zero error
Any indication that a measuring system gives a false reading when the true value of a measured quantity is zero
Data which has been shown to be valid
A proposal intended to explain certain facts or observations.
The quantity between readings
Precise measurements are ones in which there is very little spread about the mean value
Can precision give an indication how accurate data is?
No. Precision depends only on the extent of random errors – it gives no indication of how close results are to the true value.
A prediction is a statement suggesting what will happen in the future, based on observation, experience or a hypothesis.
The maximum and minimum values of the independent or dependent variables
A measurement is reproducible if the investigation is repeated by another person, or by using different equipment or techniques, and the same results are obtained.
A measurement is repeatable if the original experimenter repeats the investigation using same method and equipment and obtains the same results.
This is the smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading.
What is a sketch graph?
A line graph, not necessarily on a grid, that shows the general shape of the relationship between two variables.
Does a sketch graph need a scale or plotted points?
No. It will not have any points plotted and although the axes should be labelled they may not be scaled.
Define true value
This is the value that would be obtained in an ideal measurement
The interval within which the true value can be expected to lie, with a given level of confidence or probability.
Suitability of the investigative procedure to answer the question being asked.
Define valid conclusion
A conclusion supported by valid data, obtained from an appropriate experimental design and based on sound reasoning.