Transforming and adjusting your data

20

5

Transforming and adjusting your data

Data transformations

Relativisations

Dealing with zeros

Transposing data

Transposing environmental variables

5.1

Data transformations

The values in the working data grids can be transformed using a variety of functions.

From the working data window select Transform in the Type of Adjustment panel.

The possible relative measures available within ECOM are given below. Select the

transformation to be made and click on Submit to make the change.  The

transformation options within ECOM are itemised below.

Revert to raw   This will cause the working data to revert to the raw data, so that

you can start your investigations again.

Log

10

   Each value is transformed to the log to base 10. This cannot be done for

numbers <= 0.

Log

10(x+1)

   Each value is transformed by adding 1 and then calculating the log to

base 10. This is used when the data contains zero values.

Log

e

   Each value is transformed to the log to base e (natural logs). This cannot be

done for numbers <= 0.

Log

e (x+1)

   Each value is transformed by adding 1 and then calculating the log to

base e. This is used when the data contains zero values.

Square root   the square root of each number is calculated. This cannot be done for

negative numbers.

Arcsin   The Arcsin of each value is calculated. A transformation often used for

percentage data.

Arcsin root   The Arcsin of the square root of each number is calculated.

Power   Each value, x, is transformed to x

a

, where a is chosen by the user.

Add constant   A constant value, chosen by the user, is added to each value.

Subtract constant   A constant value, chosen by the user is subtracted from each

value.

Multiply by constant   Each value is multiplied by a constant value chosen by the

user.

Divide by constant   Each value is divided by a constant value chosen by the user.

See also:

Transforming environmental variables

Copyright 2004  PISCES Conservation Ltd