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Topic 1: Statistical Analysis
1.1.1 State that error bars are graphical representation of the variability of data
Error bars are a graphical representation of the variability of data – it can be used to show either the range of the data or the standard deviation
1.1.2 Calculate the mean and standard deviation of a set of values
 Mean calculation: Sum of all data ÷ number of data
 Standard deviation calculation (using calculator): Plot data in “List” → 2nd → “STAT” → “MATH” → 7 → insert “List” → “Enter”
1.1.3 State that the term standard deviation is used to summarize the spread of values around the mean, and that 68% of the values fall within one
standard deviation of the mean
Standard deviation: used to summarize the spread of values around the mean, and In a normal distribution curve 68% of the value fall within one
standard deviation of the mean and 95% of the data will fall within ±2 standard deviation of the mean
1.1.4 Explain how the standard deviation is useful for comparing the means and the spread of data between two or more samples
Small standard deviation = data is clustered closely around the mean value; Large standard deviation = date is widely spread around the mean value
1.1.5 Deduce the significance of the difference between two sets of data using calculated values for t and the appropriate tables
 For a T-test to be applied, the data must have a normal distribution and a sample size of at least 10
 T-test is used to find out whether there is a significant difference between the means of two populations
1.1.6 Explain the existence of a correlation does not establish that there is a casual relationship between two variables
Correlation is not a proof of cause – one factor may not necessarily be linked to the cause of change in another, and the two variables may be
correlated due to a third variable
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