# Measurement and Error Key Words

A few key words that are useful when collecting and evaluating data. Should be apt to most exam boards. General physics terms.

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• Created by: Rebecca
• Created on: 21-04-10 10:44

## Measurements

• Reliable
• The same value is obtainted each time the experiment is carried out (within acceptable limits)
• Valid
• The measurements you are making will give you the data asked for or can be used to find the required data
• Accuracy
• Accurately calibrated instruments have been used
• How confident you are that your results are right
• Precision
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## Data Analysis

• Range
• Difference between the highest and lowest value
• Uncertainty
• Also known as the probable error of the measurement
• Half the range
• OR half the smallest division on the measuring equipment
• Written as +_ the uncertainty (Can't get the real symbol on the computer but the minus is under the plus)
• Mean Value
• Add all the measurements together and divide by how many you have
• You might need to include the uncertainty when quoting the mean value
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## Errors

• Systematic
• If all the values are out by a specific amount, can be caused by a zero error on the measuring equipment
• Must be accounted for when plotting graph and taking measurements
• Random
• No differences, patterns, trends or bias.
• Often fluctuate around real value so line of best fit can show the real value
• Zero
• When the measuring device is supposed to be at zero it shows a different number
• As long as this is factored into the results, it shouldn't cause a problem
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