Chapter 28: The MEANS Procedure

Overview: MEANS Procedure

What Does the MEANS Procedure Do?

The MEANS procedure provides data summarization tools to compute descriptive statistics for variables across all observations and within groups of observations. For example, PROC MEANS

• calculates descriptive statistics based on moments

• estimates quantiles, which includes the median

• calculates confidence limits for the mean

• identifies extreme values

• performs a t test.

By default, PROC MEANS displays output. You can also use the OUTPUT statement to store the statistics in a SAS data set.

PROC MEANS and PROC SUMMARY are very similar; see Chapter 47, The SUMMARY Procedure, on page 1191 for an explanation of the differences.

What Types of Output Does PROC MEANS Produce?

PROC MEANS Default Output

Output 28.1 shows the default output that PROC MEANS displays. The data set that PROC MEANS analyzes contains the integers 1 through 10. The output reports the number of observations, the mean, the standard deviation, the minimum value, and the maximum value. The statements that produce the output follow:

 proc means data=OnetoTen;  run; 

Output 28.1: The Default Descriptive Statistics

 The SAS System                                  1                          The MEANS Procedure                        Analysis Variable : Integer   N           Mean         Std Dev         Minimum          Maximum  ------------------------------------------------------------------ 10      5.5000000       3.0276504       1.0000000       10.0000000  ------------------------------------------------------------------ 

 

PROC MEANS Customized Output

Output 28.2 shows the results of a more extensive analysis of two variables, MoneyRaised and HoursVolunteered. The analysis data set contains information about the amount of money raised and the number of hours volunteered by high-school students for a local charity. PROC MEANS uses six combinations of two categorical variables to compute the number of observations, the mean, and the range. The first variable, School, has two values and the other variable, Year, has three values. For an explanation of the program that produces the output, see Example 11 on page 581.

Output 28.2: Specified Statistics for Class Levels and Identification of Maximum Values

 Summary of Volunteer Work by School and Year               1                               The MEANS Procedure                           N  School           Year  Obs  Variable           N           Mean         Range  ----------------------------------------------------------------------------- Kennedy          1992   15  MoneyRaised       15     29.0800000    39.7500000                              HoursVolunteered  15     22.1333333    30.0000000                   1993   20  MoneyRaised       20     28.5660000    23.5600000                              HoursVolunteered  20     19.2000000    20.0000000                   1994   18  MoneyRaised       18     31.5794444    65.4400000                              HoursVolunteered  18     24.2777778    15.0000000  Monroe           1992   16  MoneyRaised       16     28.5450000    48.2700000                              HoursVolunteered  16     18.8125000    38.0000000                   1993   12  MoneyRaised       12     28.0500000    52.4600000                              HoursVolunteered  12     15.8333333    21.0000000                   1994   28  MoneyRaised       28     29.4100000    73.5300000                              HoursVolunteered  28     19.1428571    26.0000000  -----------------------------------------------------------------------------             Best Results: Most Money Raised and Most Hours Worked           2                                        Most     Most      Money     Hours     Obs School  Year   _TYPE_   _FREQ_ Cash     Time     Raised  Volunteered       1            .      0       109  Willard  Tonya     78.65       40       2         1992      1        31  Tonya    Tonya     55.16       40       3         1993      1        32  Cameron  Amy       65.44       31       4         1994      1        46  Willard  L.T.      78.65       33       5 Kennedy    .      2        53  Luther   Jay       72.22       35       6 Monroe     .      2        56  Willard  Tonya     78.65       40       7 Kennedy 1992      3        15  Thelma   Jay       52.63       35       8 Kennedy 1993      3        20  Bill     Amy       42.23       31       9 Kennedy 1994      3        18  Luther   Che-Min   72.22       33      10 Monroe  1992      3        16  Tonya    Tonya     55.16       40      11 Monroe  1993      3        12  Cameron  Myrtle    65.44       26      12 Monroe  1994      3        28  Willard  L.T.      78.65       33 

 

In addition to the report, the program also creates an output data set (located on page 2 of the output) that identifies the students who raised the most money and who volunteered the most time over all the combinations of School and Year and within the combinations of School and Year:

• The first observation in the data set shows the students with the maximum values overall for MoneyRaised and HoursVolunteered.

• Observations 2 through 4 show the students with the maximum values for each year, regardless of school.

• Observations 5 and 6 show the students with the maximum values for each school, regardless of year.

• Observations 7 through 12 show the students with the maximum values for each school-year combination.