Using Spreadsheets

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• This presentation covers some ways you can use MS Excel to make statistics easier

• If you enjoy using Excel, you will probably find some more ways yourself!

• Caution! Although spreadsheets do not make calculation errors, if the data or formula entered is wrong, the answer will be, too! So always check any answers for plausibility.

Stats you can do with Excel

• Find the mean, median, mode, standard deviation and quartiles of a list of numbers

• Set up formulae to find the mean and standard deviation of data in a table

• Find Pearson’s correlation coefficient and the equation of the best straight line

Entering Data & Formulae

• Enter your data in one column (for a list of numbers) or two adjacent columns (for correlation or tables)

• We’ll assume throughout your data is in cells A1 to A10 (a list) cells A1 to A10 and B1 to B10 (correlation or table)

• Choose an empty cell to enter your formula

Mean, Median, Mode, Standard Deviation, Quartiles

• Mean: enter =average(A1:A10)• Median: enter =median(A1:A10)• Mode: enter =mode(A1:A10)• Standard deviation: enter =stdevp(A1:A10)• Standard deviation – to use sample to estimate

for the entire population: enter =stdev(A1:A10)• Lower quartile: enter =quartile(A1:A10,1)• Upper quartile: enter =quartile(A1:A10,3)

Mean & Standard Deviation From A Table 1

• Enter the midpoints of the categories in column A, and the numbers of things in column B

• In cell C1, enter the formula =A1*B1

• In cell D1, enter the formula =A1^2*B1

5 2 =A1*B1 =A1 2̂*B115 325 835 445 2

midpoints

frequencies

Mean & Standard Deviation From A Table 2

• Copy the formulae down the columns by selecting cells C1, D1 and as far down the columns as you want to copy, then pressing CTRL and D

• Now you need to sum the values in columns B, C, D. In cell E1 enter the formula =sum(B1:B10) In cell F1 enter the formula =sum(C1:C10)

In cell G1 enter the formula =sum(D1:D10) • To find the mean, in cell H1 enter the formula =F1/E1• To find the standard deviation, in a spare cell enter the

formula =(G1/E1-H1^2)^0.5

Finding Pearson’s Correlation

• Put your data in cells A1 to A10 and B1 to B10 (or as far down the column as you need to go)

• In a spare cell, type the formula

=pearson(A1:A10,B1:B10)

Equation of Best Straight Line

• Put your data in columns A and B, with x-values in column A, y in column B

• The equation of the best straight line is in the form y = a + bx

• To find a, in a spare cell enter=intercept(B1:B10,A1:A10)

• To find b, in a spare cell enter=slope(B1:B10,A1:A10)

YES! The B’s and A’s ARE

meant to be that way round!