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What conclusions can we make from data? - OCR 21st CenturyAnalysing data

It is important to process and present data in a way which makes it easy to analyse. It is also important to evaluate the quality of data before drawing a conclusion.

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Analysing data

Patterns and trends

Once a graph has been drawn it can be analysed to look for patterns and trends.

A scatter graph has points plotted low at first but with a steady increase in height.
A scatter graph has points plotted high at first but with a steady decrease in height.

If the dependent variable increases as the independent variable increases, there is a positive correlation.

If the dependent variable decreases as the independent variable increases, there is a negative correlation.

A line graph. This one shows the line starting at 5 on the Y axis and increasing steadily
A line graph. This one shows the line starting at 0 on the Y axis and increasing steadily.

If the graph is a straight line, the relationship is linear. The equation for the line is of the form y = mx + c.

If the straight line graph passes through the origin, the dependent variable is directly proportional to the dependent variable. The equation for the line is of the form y = mx.

Curves may show a squared relationship (y = mx2), an inverse proportional relationship (y = m 梅 x), or an inverse squared relationship (y = m 梅 x2).

A curve graph. This one shows a gradually increasing curve.
Squared
A curve graph. This one shows a gradually decreasing curve.
Inverse proportional
A curve graph. This one shows a dramatically decreasing curve.
Inverse squared
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Evaluating data
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Using units

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