AQA practical terms

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  • Created by: Rchilds
  • Created on: 15-05-17 20:48
What does resolution mean?
This is the smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading. Always write this as a number e.g. 0.01 not as how many decimal places e.g 2 decimal places
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What does repeatable mean?
You repeat YOUR OWN experiment using the same equipment and variables and get the same patterm
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What does reproducible mean?
Someone else performs an experiment with the same variables as your own and sees the same PATTERN
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How do you comment on the pattern in a graph?
(1) state the basic pattern - as the x-axis value increases, the y-axis value increases/decreases (2) comment on whether it's a straight line or curve. If it is a curve, say if it's falling or rising fastest at the start or end (continued on next)
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graph comments continued
(3) comment on any significant points eg. when it changes direction, is a min/max, or crosses another graph or turns from being a straight line into a curve etc. Read down form this point to the x-axis and give the exact number that this happens at.
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What is continuous data?
Data that can take any value
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What is categoric data?
Data that can only take certain, defined values
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What type of graph do you use if both sets of data are continuous data?
Line graph
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What type of graph o you plot if one variable is catagoric?
Bar Chart
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When is it best to use a pie chart?
When comparing proportions of something. eg. %
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What is a control variable?
A 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 (to keep it a fair test).
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What is the independant variable?
The thing you change
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What is the dependent variable?
The thing you measure
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Why are dataloggers good for collecting data?
It can take readings automatically, more frequently, more accurate, don't need to remove probes to take reading from scale, can take readings with a better resolution, there is no reading error from humans (it is digital)
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What is a control? (not a control variable)
When you run an investigation without the independent variable present to see how the dependant variable changes naturally, you can then account for this in your results.
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What is an anomaly?
A result that doesn't fit the pattern
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Why is it good to repeat investigations?
To check for anomalies (makes it repeatable)
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Why is it good for you to comapre your results with others or the have your work peer reviewed?
To check you haven't made a mistake that effects all of your data e.g. forgotten to control a variable
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What is accuracy?
How close you are to the true value, you can improve this by repeating and averaging
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What is precision?
How close your repeats are to the mean, or points are to the line of best fit (scatter). This could be due to random errors.
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What is a range?
The maximum value to minimum value of some data
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What do you need to remember when drawing tables?
Title every column with exactly what it shows e.g. 'force' not just 'test 1'. Put a unit in every column title (not next to the numbers). If you calculate values e.g. the mean, they should be written to the same significant figures as the raw data
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What do you need to remember when drawing graphs?
Label each axis anf put a unit. Use a sensible scale (go up in 1, 2, 5, 10 etc not 3, 7... and go up by the same amount for each box). Make your graph as big as possible. Plot points with an X not a dot.
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What is a random error?
An error in your data that causes your measured point to be different from the true value by a random amount each time. It causes scatter and anomalies.
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What is a systematic error?
An error affects your data in the same way each time e.g. always too big by 0.1. This is usually there because you have forgotten to account for something and you can only find these by comparing your results to others.
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How do you reduce the effect of random errors?
Repeat and average. Plot lots of points on your graph so you can be more confident with your line of best fit (pattern)
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How do you reduce the effect of systematic errors?
Systematic errors cannot be dealt with by simple repeats. 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.
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What does a linear relationship look like?
A straight line graph
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What does a proportional relationship look like?
a straight line graph THAT ALSO go through the origin
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How should you approach calculation questions?
Look at what you are asked to calculate, go straight to the formula sheet and find the equation that has this keyword in. Copy it down. Look for keywords in the question that have values or look at units. Substitute these in first then rearrange
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What are digital readings better than analogue readings (from scales)?
Digital gives you the exact number and can often read to more decimal places (better resolution). You might need to estimate values on an analogue scale if the result is between markings
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How do you tell if something is directly proportional?
The dependant variable values should increase by the same amount each time the independent variable increases
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What should you do if data collected does fit your prediction?
1) repeat 2) look for anomalies 3) if still doesn't fit, reconsider your prediction
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Other cards in this set

Card 2

Front

What does repeatable mean?

Back

You repeat YOUR OWN experiment using the same equipment and variables and get the same patterm

Card 3

Front

What does reproducible mean?

Back

Preview of the front of card 3

Card 4

Front

How do you comment on the pattern in a graph?

Back

Preview of the front of card 4

Card 5

Front

graph comments continued

Back

Preview of the front of card 5
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