# GCSE AQA's ISA (Individual Skills Assignments)

Just the keywords variables you need to know and stuff...

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• Created on: 15-02-11 21:30

Accuracy

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## Accuracy

How close to the true value a measurement or result is.

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Calibration

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## Calibration

Fixing known points on a measuring instrument and marking a scale on the measuring instrument between the fixed points.

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Data

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## Data

A collection of measurements

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Datum

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## Datum

A singular of Data.

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Random Errors

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## Random Errors

Causes readings or mesasurements to be different to the true value
Random errors are caused by
-Human errors
-Faulty technique in taking measurements
-Faulty equipment

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Systematic Error

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## Systematic Error

All readings are shifted one way or the other from the true value-

all the readings taken will be affected in the same way.

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Zero Errors

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## Zero Errors

When a measuring equipment has a false zero (e.g. when an ammeter shows a current reading even though there is no current flowing through it).

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Evidence

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## Evidence

Data subjected to some form of validation.

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Fair Test

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## Fair Test

When all other variables except the independent variable have been kept constant and controlled, so that only the independent variable can affect the outcome of the investigation.

Also, a fair test is done without any bias

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Precision

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## Precision

The precision of of a measurement is determined by the limits of the scale (the smallest scale reading) on the instrument being used.
The smaller the scale reading on the measuring equipment, the more precise the investigation.

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Reliability

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## Reliablity

To see if a test is reliable, we can

-repeat the experiment and see that the results are similar.
To improve the accuracy and reliablity there even more, we can make an average of the results.
This way it will also be more valid.

-Check someone else's results and compare them- if it's similar, we can tell the experiment is reliable.

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True Value

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## True Value

The accurate value which would be found if the test was carried out and quantities were measured WITHOUT ANY ERRORS at all.

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Validity

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## Validity

-Your experiment is valid if you have run a fair test.

-Only the independent variable(s) have been changed to affect the outcome of the result.

-All other variables (the control variables) have been kept constant and controlled.

-It needs to be reliable and precise to be valid.

-It is not a fair test if there is bias.

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Categoric Variable

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## Categoric Variable

Values that can be described with labels (e.g. eye colour, etc)
It is used in bar graphs or pie charts.

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Discrete Variable

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## Discrete Variable

A type of categoric variable where the values are restricted to whole numbers

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Ordered Variable

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## Ordered Variable

A type of categoric variable that can be ranked.
(e.g. the size of marble chips: small, medium or large)

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Continuous Variable

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## Continuous variable

A variable that can have any numerical value (e.g. height, mass, length, temperature)

-USE A LINE GRAPH to show results-

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Independent Variable

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## Independent Variable

The variable for which the values are changed or selected intentionally to see how it affects the outcome of the investigation.

-Found in the first column of a table
-Found in the X Axis in a graph.

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Dependent Variable

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## Dependent Variable

The dependent variable is the value that you measure for each and every change in the independent variable.

This is on the Y Axis

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Control Variable

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## Control Variable

In addition to the Independent variable, this too may affect the outcome of the investigation.

To prevent that from happening, you must keep all the variables constant and the same/ controlled.

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