Arithmetic expressions

When we said C2-C3 in the first example, that was an arithmetic expression meaning (obviously) the value in column 2 minus the value in column 3. Many other operations are available, and here is a complete list:

x - y: x MINUS y
x + y: x PLUS y
x mod y: x MODULO y
x / y: x DIVIDED BY y
x * y: x TIMES y
x pow y: x TO THE yTH POWER
x pX y: PROBABILITY OF CHI-SQUARED x WITH y DEGREES OF FREEDOM
x pT y: PROBABILITY OF STUDENT'S T x WITH y DEGREES OF FREEDOM
- x: NEGATIVE x
abs x: ABSOLUTE VALUE OF x
pN x: ONE-TAILED CUMULATIVE PROBABILITY OF x IN A NORMAL DISTRIBUTION
log x: LOG x BASE 10
ln x: NATURAL LOG OF x (base e)
exp x: e TO THE xTH POWER (natural antilog)
sin x: SIN x RADIANS
arcsin x: ARCSIN x IN RADIANS
cos x: COS x RADIANS
arccos x: ARCCOS x IN RADIANS
tan x: TAN x RADIANS
arctan x: ARCTAN x IN RADIANS

Arithmetic expressions can be written out just as they would appear on paper, again with brackets to clarify the order of operations:

c3+c4*6
(c3+c4)*6
(c4*c5)pow3
(c4*c5*c6)pow(1/3)

The last example takes the geometric mean of columns 4, 5, and 6. It multiplies them together and then takes the cube root of the product.

c13 pX 3

This example would take the value in column 13 to be a chi-squared statistic with three degrees of freedom and computes its probablility, or p value. See the section on the ARITHMETIC command for details of how to use EASISTAT as a set of statistics tables to look up.

Numbers can be written for arithmetic expressions either as ordinary decimal numbers (37, -45.236, 11.4) or using exponential notation, where the mantissa is followed immediately by an E and the power of ten to multiply it by. Thus 3.3e5 is the same as 330000 and 2.7e-4 means 0.00027. The results of the ARITHMETIC command are output in this format where appropriate.