Topic One. Statistical Analysis. Variability of data. All living things vary, even two peas in the same pod, so how do we measure this variation? We plot data usually using the mean, but error bars are a graphical representation of variability of data. Error bars show;
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either showing range (highest & lowest value)
or showing standard deviation (±1 s.d.)
We can then measure the deviation or variance from the mean
Evaluation of the variance of the mean usefulWhat is important about normally distributed data?
If the data is tightly clustered there will be small variances, but if the data is more evenly spread over the whole range, the variance would be bigger
1.1.3 State-standard deviation summarizes the spread of values around the means and 68% of the values fall within one standard deviation and 95% of values fall within two standard deviations
Visit values around the means and www.mymaths.co.uk
Click on GCSE statistics - then standard deviation
Calculate mean and standard deviation from frequency table
Assume these bars were for values around the means and ±1 s.d.
Comment on significance