SHAZAM Commands
Commands give instructions to SHAZAM. Commands tell
SHAZAM to perform a certain task.
Many SHAZAM commands also have options that instruct SHAZAM
to perform additional tasks. Options are listed after a /
character and can be specified in any order.
A complete description of SHAZAM commands is given in the
SHAZAM User's Reference Manual.
Some important SHAZAM commands that are introduced here are:
An online reference guide to all SHAZAM commands
is available.
Notes
 Commands and command options have names. Shortened names are allowed.
For example, the
SAMPLE command can be referred to as
SAMP .
On the READ command the SKIPLINES=
option can be referred to as SKIP= .
 Commands can have continuation lines. If a command is terminated
with the & character this indicates that the command is continued
on the next line. An example of the use of continuation lines follows:
READ (KLEIN.txt) WG T G TIME PLAG KLAG XLAG &
C I W1 P WGWP X 
 Variable name lists can be abbreviated by the use of a numbered
range list. The variables in a numbered range list
have the identical name, except for the last character or characters,
which are consecutive numbers.
For example, the following two commands are equivalent.
 In general, SHAZAM commands are not case sensitive. That is,
upper case and lower case is interchangeable. However, if you wish
to distinguish upper and lower case variables and file names in
SHAZAM then use the command:
SET NOLCUC .
[SHAZAM Guide home]
The SAMPLE command
The SAMPLE command sets the sample range of the data.
The general command format is:
where beg and end are numbers specifying the beginning and ending
observations to use for subsequent calculations.
Example
The Theil textile data set has 17 observations
on each variable and so the SAMPLE command should be:
To restrict the analysis to start in observation 3 and end in
observation 14 the appropriate SAMPLE command is:
The READ command
The READ command loads the data set into SHAZAM
memory and assigns variable names. The general command format is:
READ (filename) vars / options

where filename is the data filename, vars is a list of user assigned
variable names, and options is a list of desired
options. All the variables listed must have the same number of
observations. Some useful options are:
BYVAR 
Read the data by variable.
The data file must be prepared so that all observations for each new
variable begin on a new line (more than 1 line can be used).

NOBYVAR 
Read the data by observation.
The data file must be prepared so that observations for all variables
begin on a new line (more than 1 line can be used). This is the default option.

LIST 
List all the data on the output file.

SKIPLINES=n 
Skips the number of lines specified
before reading data from the data file. This option is required when
the data file contains a header of descriptive information.

Rules for preparing data files for SHAZAM
can be viewed. Instructions are also available for
working with Microsoft Excel XLS files.
Example 1  Loading data from a data file
For the Theil textile data set each line
of the data file contains one observation on the 4 variables.
The following command assigns variable names and loads the data from the
file THEIL.txt into SHAZAM memory.
SAMPLE 1 17
READ (THEIL.txt) YEAR CONSUME INCOME PRICE 
The next command shows the use of the LIST option.
This option instructs SHAZAM to list the data set on the output file.
This can be very useful for checking that the data set has
been read in correctly.
SAMPLE 1 17
READ (THEIL.txt) YEAR CONSUME INCOME PRICE / LIST

Example 2  Small data sets  working without data files
Consider a data set with observations on height (inches) and
weight (pounds) for 6 individuals (this example is from
Chotikapanich and Griffiths, 1993). The data can be entered directly
in the SHAZAM command file immediately following the READ
command as follows.
SAMPLE 1 6
READ HEIGHT WEIGHT
69 112
56 84
62 102
67 135
70 165
63 120

An alternative way of setting up the command file is to use the
BYVAR option on the READ command as
follows.
SAMPLE 1 6
READ HEIGHT WEIGHT / BYVAR
69 56 62 67 70 63
112 84 102 135 165 120

Another way of reading this simple data set is to use two
READ commands (one for each variable) as follows.
SAMPLE 1 6
READ HEIGHT / BYVAR
69 56 62 67 70 63
READ WEIGHT / BYVAR
112 84 102 135 165 120

The GENR command
The GENR command will create new variables from old
ones and do a variety of data transformations. The general command
format is:
where var is a userassigned name of the variable to be generated and
equation is an arithmetic expression which involves variables, scalars
and mathematical functions.
The following mathematical operators may be used:
 unary functions (see list below)
 ** (exponentiation)

* , / (multiplication, division)

+ ,  (addition, subtraction)

.EQ., .NE. , .GE. , .GT. , .LE. , .LT.
(relational operators)

.NOT. (logical operator)

.AND. (logical operator)

.OR. (logical operator)
The arithmetic expression that is given after the equal
sign (=) is evaluated (any variable that is given in this expression
must already exist). The result is saved in the variable that
appears before the equal sign. If the result variable does not exist
then SHAZAM will create it. If the result variable is already created
then SHAZAM will replace the old variable with the new results.
On the GENR command arithmetic expressions are
evaluated from left to right. However, some operators take priority.
The order of operations conforms to the priority levels given above.
Expressions in parentheses are always evaluated first.
Therefore, to avoid confusion use as many levels of parentheses
as desired.
The available unary functions are:
ABS(x) 
absolute value 
DUM(x) 
dummy variable generator 
EXP(x) 
exp(x) 
INT(x) 
integer truncation 
LAG(x) 
lag a variable one time period 
LAG(x,n) 
lag a variable n time periods 
LGAM(x) 
log gamma function 
LOG(x) 
natural logs 
MAX(x,y) 
maximum of two variables 
MIN(x,y) 
minimum of two variables 
MOD(x,y) 
modulo arithmetic, remainder of x/y 
NCDF(x) 
standard normal cumulative distribution function 
NOR(x) 
normal random number with standard deviation x 
SAMP(x) 
draw a sample with replacement from the variable x 
SEAS(x) 
seasonal dummy variable with periodicity x 
SIN(x) 
sine (x measured in radians) 
SIN(x,1) 
arcsine (defined for x in the interval [ 1,1]) 
SQRT(x) 
square roots 
SUM(x) 
cumulative sum of variable x 
SUM(x,n) 
sum of n observations on variable x starting at observation 1 
TIME(x) 
time index plus x 
UNI(x) 
uniform random number with range (0,x) 
Example 1  Computing a reciprocal
To compute the reciprocal of each observation in the variable
A and save the result in the variable B
the command to use is:
Example 2  Taking logarithms
When working with macroeconomic time series it is very common
to use logtransformed variables in the analysis. To get the
logarithm of each observation in the variable CONSUME and save
the result in the new variable LCONS the command to use is:
Example 3  Computing a percentage change
To compute the percentage rate of change in the variable WAGE
and save the results in the variable WR the command to use is:
GENR WR=100*(WAGELAG(WAGE))/LAG(WAGE) 
Note that the LAG function is used to take a 1period lag.
This function must be used with some care. The first observation will
be assigned to 0. Therefore, for subsequent analysis with the
WR variable, the SAMPLE command must be set
to start at observation number 2.
The same calculation can be done with two GENR
commands as follows:
GENR LWAGE=LAG(WAGE)
GENR WR=100*(WAGELWAGE)/LWAGE

Example 4  The exponentiation operator **
The command 
GENR E2=E**2 
is the same as 
GENR E2=E*E 
The command 
GENR SD=SQRT(VAR) 
is the same as 
GENR SD=VAR**(0.5) 
More examples are in the SHAZAM User's Reference Manual.
The GEN1 command
The GEN1 command is used for scalar arithmetic.
The general command format is:
where var is a userassigned name of the scalar variable to be generated
and equation is an arithmetic expression.
The GEN1 command is equivalent to using a
SAMPLE 1 1 command with a
GENR command to generate a variable with only
1 observation.
Example
To compute the logarithm of 2 and save the
result in the variable L2PI the command to use is:
Note the use of the variable $PI . In general, variables
that start with a $ are special SHAZAM temporary variables.
The SHAZAM variable $PI contains the value of
set at 3.1415926535898 .
(On the SHAZAM output not all digits are printed).
The PRINT command
The PRINT command is used to list variables on the
SHAZAM output file. Note that this command does not direct output to the
printer. The general command format is:
where vars is a list of variable names and options is a list of desired
options. Some useful options are:
BEG= 
Specifies the first observation to be printed.

END= 
Specifies the last observation to be printed.

If the above options are not used then the range set
by the SAMPLE command is used.
Example
To list the variables in the Theil textile
data set the command to use is:
PRINT YEAR CONSUME INCOME PRICE 
To list the data on CONSUME and PRICE
for the final 6 observations the command to use is:
PRINT CONSUME PRICE / BEG=12 END=17 
The WRITE command
The WRITE command is used to write variables
to a file. The general command format is:
WRITE (filename) vars / options

where filename is the data filename, vars is a list of variable names,
and options is a list of desired options. The available options on
the WRITE command are similar to those available for the
READ and PRINT commands.
The SET command
The SET command is used to set options that affect
the way SHAZAM does its work. The SET command has some
useful options for controlling the amount of detail that appears on
the output file. Some other uses of the SET command are
contained in this guide.
In general, the format to turn on features is:
and the format to turn off features is:
where option is the desired option. A complete description of available
options is in the SHAZAM User's Reference Manual.
The SKIPIF command
The SKIPIF command is used to specify conditions
under which observations are to be skipped in subsequent SHAZAM commands.
The general command format is:
where the expression is an arithmetic expression as described for the
GENR command.
For each observation, the expression is evaluated and if the result is
positive (or true) the observation is excluded from the sample.
The expression may use the following relational operators.
Operator  Meaning 
.EQ.  Equal (=) 
.NE.  Not Equal 
.GE.  Greater than or equal 
.GT.  Greater than (>) 
.LE.  Less than or equal
() 
.LT.  Less than (<) 
Note that the operators must start and terminate with a dot (.).
Upper case and lower case are interchangeable.
An example of the SKIPIF command is:
The above command will skip observations when the value of the
variable XVAL is less than or equal to 5.1.
Eliminating SKIPIF
After working with a subset of observations it may be useful to
return to data analysis with the full sample.
This can be done by eliminating all SKIPIF commands
with the command:
Note that the $ character in SKIP$ is a
special character for SHAZAM variable names.
SKIPIF Messages
The SKIPIF command lists the skipped observations
on the SHAZAM output file. If a large number of observations have
been skipped then the output listing can be lengthy. These
messages can be suppressed by using the command:
More Documentation
More discussion on the use of the SKIPIF command
is given in the SHAZAM User's Reference Manual.
The STAT command
The STAT command is used to compute descriptive statistics
(including mean, standard deviation, variance, minimum and maximum).
The general command format is:
where vars is a list of variable names and options is a list of desired
options. Some useful options are:
PCOR 
Prints a correlation matrix of the variables. 
PCOV 
Prints a covariance matrix of the variables. 
PMEDIAN 
Prints the median, mode, quartiles and interquartile range
for each variable. 
MEAN= 
Stores the means as a vector in the variable specified.

STDEV= 
Stores the standard deviations as a vector in the
variable specified. 
SUMS= 
Stores the sum of each variable as a vector in the
variable specified. 
Note that, in general, options that begin with the letter
P are used to print results on the SHAZAM output file.
Options ending in an = sign are used to save results in the variable
specified.
Example
Consider the problem of finding the correlation between height and
weight for a sample of 6 individuals. The SHAZAM commands below can be used
to get the answer.
SAMPLE 1 6
READ HEIGHT WEIGHT / BYVAR
69 56 62 67 70 63
112 84 102 135 165 120
STAT HEIGHT WEIGHT / PCOR
STOP

The SHAZAM output follows:
_SAMPLE 1 6
_READ HEIGHT WEIGHT / BYVAR
2 VARIABLES AND 6 OBSERVATIONS STARTING AT OBS 1
_STAT HEIGHT WEIGHT / PCOR
NAME N MEAN ST. DEV VARIANCE MINIMUM MAXIMUM
HEIGHT 6 64.500 5.2440 27.500 56.000 70.000
WEIGHT 6 119.67 28.048 786.67 84.000 165.00
CORRELATION MATRIX OF VARIABLES  6 OBSERVATIONS
HEIGHT 1.0000
WEIGHT 0.81587 1.0000
HEIGHT WEIGHT
_STOP
 
The output shows that the correlation between height and weight is:
0.81587 .
The STOP command
The STOP command is used to terminate the SHAZAM run.
The format of the command is:
