AQA Key Terms Flashcards
Define accuracy
A measurement result is considered accurate if it is judged to be close to the true value.
Define calibration
Marking a scale on a measuring instrument
Define data
Information, either qualitative or quantitative, that has been collected
Define measurement error
The difference between a measured value and the true value
Define anomaly
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 repeat 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?
No
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
Define evidence
Data which has been shown to be valid
Define hypothesis
A proposal intended to explain certain facts or observations.
Define interval
The quantity between readings
Define precision
Precise measurements are ones in which there is very little spread about the mean value. Repeat readings should be very similar to each other
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.
Define prediction
A prediction is a statement suggesting what will happen in the future, based on observation, experience or a hypothesis.
Define range
The maximum and minimum values of the independent or dependent variables
Define reproducible
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.
Define repeatable
A measurement is repeatable if the original experimenter repeats the investigation using same method and equipment and obtains the same results.
Define resolution
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
Define uncertainty
The interval within which the true value can be expected to lie, with a given level of confidence or probability.
Define validity
Suitability of the investigative procedure to answer the question being asked. Only the 1 independent variable has been changed
Define valid conclusion
A conclusion supported by valid data, obtained from an appropriate experimental design and based on sound reasoning.
Define variables
These are physical, chemical or biological quantities or characteristics.
Define categoric variable
Categoric variables have values that are labels, eg names of plants or types of material.
Define continuous variable
Continuous variables can have any numerical value
Define control variable
Control variable is one which may, in addition to the independent variable, affect the outcome of the investigation and therefore has to be kept constant or at least monitored.
Define independent variable
Independent variable is the variable for which values are changed or selected by the investigator.
Define dependent variable
Dependent variable is the variable of which the value is measured for each and every change in the independent variable.
What word is udes to describe a measurement close to the true value?
Accurate
Placing a thermometer in melting ice to check whether it reads 0 °C is an example of ?
Checking calibration
What term do we use for information that we have collected?
Data
What is the term for the difference between the measured value and the true value
Measurement error
What do we call values that are not close to the true value and out of the range of uncertainty?
Anomalies
What type of error causes readings to differ from the true value by a consistent amount each time a measurement is made?
Systematic error
If the needle of an ammeter fails to return to 0 what type of error is this?
Zero error
If our data is shown to be valid what do we call it?
Evidence
What do we call a proposal to explain certain facts or observations?
A hypothesis
What is the word for the quantity between readings?
Interval
If all of my results are very close to my mean value I can say they are what?
Precise
What do I call a statement suggesting what will happen in the future, based on observation, experience or a hypothesis.
A prediction
If I said my data was 0-50cm what am I giving you?
The range
If you repeat an experiment with the same method/equipment and get the same results you can say your data is what?
Repeatable
If someone else repeats your experiment and gets the same results you can say your data is what?
Reproducible
If you repeat an experiment with different equipment or a different technique and get the same results you can say your data is what?
Reproducible
What is the word for the smallest change in quantity an instument can measure?
Resolution
What do we call the the value that would be obtained in an ideal measurement?
The true value
An investigation to find out if the rate of a chemical reaction depended upon the concentration of one of the reactants would not be a _______ procedure if the temperature of the reactants was not controlled.
Valid
What type of variable is type of plant?
Categoric
What type of variable is height?
Continuous
In an investigation to find out if the rate of a chemical reaction depended upon the concentration of one of the reactants, what type of variable is temperature?
Control
In an investigation to find out if the rate of a chemical reaction depended upon the concentration of one of the reactants, what type of variable is concentration?
Independent
In an investigation to find out if the rate of a chemical reaction depended upon the concentration of one of the reactants, what type of variable is the rate?
Dependent
What is the name for the variable that the investigator changes?
Independent variable
What is the name for the variable that the investigator measures?
Dependent variable
What is the name for the variable that the investigator keeps the same or monitors?
Control variable
How can uncertainty be calculated for repeat readings?
Range/2
