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interquartile range used will be a different value from before).

###### Calculations required for the Main Study

1.

Scatter graphs for each group

2.

Correlation coefficient for each group

3.

Line of best fit, equation and R2 on scatter graphs (only if correlation coefficient is >0.6)

4.

Mean and standard deviation for heights (or weights) for each group

5.

Minimum, lower quartile, median, upper quartile and maximum for weights (or heights).  From this you can find the range and interquartile range and produce box and whisker diagrams (these should be done by hand on graph paper – putting them all on one sheet along the same scale will make comparisons easier)

#### Standard Deviation – Standard deviation (represented by the symbol ) looks at how spread out the data is.  It is obtained by looking at how far each individual value is away from the mean.  It is calculated using the formula:

where is the mean of the data set and n is the number of values

The larger the value obtained, the further the values are from the mean.  Standard deviation is a way of comparing two sets of data.  Standard deviation can be calculated in different ways depending upon the type of data.  In Excel the function stdevp uses the above formula which you need for your data.

To Calculate Standard Deviation in Excel:

1.

Select an empty cell

2.

Click on fx on the tool bar

3.

Select Statistical in the function category

4.

Select Stdevp in the function name and then click ok

5.

Highlight the first item in list and drag down to highlight all the data in the column, which will appear in the number 1 box (ignore number 2 box) and click ok

To Calculate the Mean in Excel:

1.

Click in a blank cell

2.

Click on fx on the tool bar

3.

Select Statistical in the function category

4.

Select Average in the function name and then click ok

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