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Excel
To open Excel in windows go Start � Programs � Microsoft Office � Excel
When it opens you will see a blank worksheet, which consists of alphabetically titled
columns and numbered rows. Each cell is referenced by its coordinates of columns and
rows, for example A1 is the cell located in column A and row 1; B7 is the cell in column B
and row 7. You can reference a range of cells, for example C1:C5 are cells in columns C
and rows 1 to 5. You can also reference a matrix, A10:C15, are cells in columns A, B and
C and rows 10 to 15.
Excel has 256 columns and 65,536 rows.
There are some shortcuts to move within the current sheet:
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�Home� moves to the first column in the current row
�End � Right Arrow� moves to the last filled cell in the current row
�End - Down Arrow� moves to the last filled cell in the current column
�Ctrl-Home� moves to cell A1
�Ctrl-End� moves to the last cell in your document (not the last cell of the current
sheet)
 �Ctrl-Shift-End� selects everything between the active cell to the last cell in the
document
To select a cell :
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Click on a cell (i.e. A10), hold the shift key, click on another cell (C15) to select the
cells between A10 and C15.
 You can also click on a cell and drag the mouse to the desire range
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To select not-adjacent cells, click on a cell, press ctrl and select another cell or range
of cells.
Excel stores your work in a workbook, each workbook has one or more worksheets
(and/or charts) which you can view by clicking on the sheet tab (lower left corner of the
active (current) sheet).
Entering data
You can type anything on a cell, in general you can enter text (or labels), numbers,
formulas (starting with the �=� sign), and logical values (as in �true� or �false�).
Click on a cell and start typing, once you finish typing press �enter� (to move to the next
cell below) or �tab� (to move to the next cell to the right)
You can write long sentences in one single cell but you may see it partially depending on
the column width of the cell (and whether the adjacent column is full). To adjust the width
of a column go to Format � Column � Width or select �AutoFit Selection�.
Numbers are assumed to be positive, if you need to enter a negative value use the minus
sign (�-�) or enclose the number in parentheses (�(number)�).
If you need to enter percentages, dollar sign, or any other symbol to identify the number
just add the �%� or �$�. You can also enter the number and change its format using
the menu: Format � Cell and select the �number� tab which has all the different
formats.
Dates are automatically stored as mm/dd/yyyy (or the default format if changed) but there
is some flexibility here. Enter month and number and excel will enter the date in the
default format. If you press �ctrl� and �;� (Crtl-;) excel will enter the current date.
Time is also entered in a default format. Enter �5 pm�, excel will write �5:00 PM�. To
enter the current time press �ctrl� and �:� (Ctrl-:)
To practice enter the following table (these data are made-up, not real)
Each column has a list of items. Column A has IDs, column B has last names of students
and so on.
Let�s say for example you do not want capital letters for the columns �Last Name� and
�First Name�. You do not want �SMITH� you want �Smith�. Two options, you can
re-type all the names or you can use the following formula (IMPORTANT: All formulas start with
the equal �=� sign):
=PROPER(cell with the text you want to change)
To get the full table:� Click here to get it.
The full table should look like this. This is a made up table, it is just a collection of random
info and data.
Exploring data in excel
Descriptive statistics (using excel�s data analysis tool)
Generally one of the first things to do with new data is to get to know it by asking some
general questions like but not limited to the following:
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What variables are included? What information are we getting?
What is the format of the variables: string, numeric, etc.?
What type of variables: categorical, continuous, and discrete?
Is this sample or population data?
After looking at the data you may want to know
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How many males/females?
What is the average age?
How many undergraduate/graduates students?
What is the average SAT score? It is the same for graduates and undergraduates?
Who reads the newspaper more frequently: men or women?
You can start answering some of these questions by looking directly at the table, for some
other questions you may have to do some calculations by obtaining a set of descriptive
statistics. These statistics are a collection of measurements of two
things: location andvariability. Location tells you the central value (the mean is the most
common measure of this) of your variables. Variability refers to the spread of the data
from the center value (i.e. variance, standard deviation). Statistics is basically the study of
what causes such variability.
Location
Variability
Mean
Variance
Mode
Standard deviation
Median
Range
Let�s get some descriptive statistics for this data. In excel go to Tools � Data Analysis. If
you do not see �data analysis� option you need to install it, go to Tools � Add-Ins, a
window will pop-up and check the �Analysis ToolPack� option, then press OK. Try
running data analysis again.
For Excel 2007 see http://office.microsoft.com/en-us/excel/HP100215691033.aspx
For Excel 2003 see http://office.microsoft.com/en-us/excel/HP011277241033.aspx�
In the pop-up window select �Descriptive Statistics� click OK.
Another window will pop-up
Let�s check this window:
Input Range: This is to select the data you want to analyze.
Once you click in the input range you need to select the cells you want to analyze.
Back to the window
Since we include the labels in first row make sure to check that option. For the output
option which is the place where excel will enter the results select O1 or you can select a
new worksheet or even new workbook.
Check �Summary statistics� and the press OK. You will get the following:
While the whole descriptive statistics cells are selected go to Format � Cells to change all
numbers to have one decimal point. When you get the �format cells� window, select the
following:
Click OK. All numbers should now have one decimal as follows:
Now we know something about our data.
The average student in this sample is 25.2 years, has a SAT score of 1848.9, got a grade
of 80.4, is 66.4 inches tall and reads the newspaper 4.9 times a week. We know this by
looking at the �mean� value on each variable.
The mean is the sum of the observations divided by the total number of observations. It is
the most common indicator of central tendency of a variable. If you look at the last two
rows: �Sum� and �Count� you can estimate the mean dividing �Sum� by �Count�
(sum/count). You can also calculate the mean using the function below (IMPORTANT: All
functions start with the equal �=� sign):
=AVERAGE(range of cells with the values of interest)
For �age�
=AVERAGE(J2:J31)
�Sum� refers to the sum of all the values in a range of values. For age means the sum
of the ages of all students. The excel function for sum is:
=SUM(range of cells with the values of interest)
�Count� refers to the count of cell that contain values (numbers). The function is:
=COUNT(range of cells with the values of interest)
�Min� is the lowest value in an array of values. The function is:
=MIN(range of cells with the values of interest)
�Max� is the largest value in an array of values. The function is:
=MAX(range of cells with the values of interest)
The �Standard Error� (SE) indicates how close the sample mean is from the �true�
population mean. The average age of 25.2 years is just an estimate of this sample of
students but it can vary had you used a different set of students. The standard error is
calculated by dividing the standard deviation of the population (or the sample) by the
square root of the total number of observations. The SE can be used to roughly define a
range of certainty for the mean. Using �age�:
Z
% Certainty
1 (0.99)
2 (1.96)
3 (2.58)
Lower bound
68%
95%
99%
Upper bound
23.9
22.7
21.4
26.5
27.7
29.0
Lower:� Mean � (SE*Z) for example 25.2 � (1.3 * 2) = 22.7
Upper:� Mean + (SE*Z) for example 25.2 + (1.3 * 2) = 27.7
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You are 68% certain that the average age is between 23.9 and 26.5 years old
You are 95% certain that the average age is between 22.7 and 27.7 years old
You are 99% certain that the average age is between 21.4 and 29.0 years old
Note that the more certainty wider the gap.
The median is another measure of central tendency. To get the median you have to order
the data from lowest to highest. The median is the number in the middle.� If the number
of cases is odd the median is the single value, for an even number of cases the median is
the average of the two numbers in the middle. The excel function is:
=MEDIAN(range of cells with the values of interest)
The mode refers to the most frequent, repeated or common number in the data. By age
there are more students 19 years old in the sample than any other group. In the SAT
scores the mode is �#N/A� which means that all values are unique. The excel function
is:
=MODE(range of cells with the values of interest)
Range is a measure of dispersion. It is simple the difference between the largest and
smallest value, �max� � �min�.
The sample variance measures the dispersion of the data from the mean. It is the simple
mean of the squared distance from the mean. It is calculated by:
SV = sum of (X-mean of X)2 / Number of observation minus 1
Higher variance means more dispersion from the mean.� The excel function is:
=VAR(range of cells with the values of interest)
The standard deviation is the squared root of the variance. Indicates how close the data is
to the mean. Assuming a normal distribution, 68% of the values are within 1 sd from the
mean, 95% within 2 sd and 99% within 3 sd. The excel formula is:
=STDEV(range of cells with the values of interest)