Ratios take two or more data items as inputs and return a factor that can typically be used to compare a security to its peers. Ratio functions typically operate on **fundamental** or **estimate** data.

### Fundamental Functions

Fundamental functions takes the following parameters:

- a mandatory
**period**parameter to denote a quarterly, annual or ltm (*last twelve months rolling sum*) period. - an optional
**period offset**parameter, which tells the system to retrieve data from*offset*periods ago. - as well as a
**working day offset**to go back*offset*working days.

Some examples are:

- PE
**(q)**- returns the price to earnings ratio for the current quarter with today's closing price. - PriceToSales
**(a, 1)**- returns price to sales ratio using the sales figure from the previous annual report and today's closing price. - ROA
**(q, 0, 20)**- the most recent quarterly return on assets as at 20 working days ago.

### Estimate Functions

Estimate functions takes the following parameters:

- a mandatory
**period**parameter to denote a quarterly or annual period. - an optional
**index**parameter, which tells the system to retrieve the estimate for*index*periods in the future. - an optional
**period offset**parameter, which tells the system to retrieve data from*offset*months ago - as well as a
**working day offset**to go back*offset*working days.

Some examples are:

- PEG
**(q)**- returns the price to earnings growth ratio for the current quarter's estimated growth and price to earnings figure with today's closing price. - PEGY
**(a, 2)**- returns the price to earnings growth ratio for the estimated growth over the next 2 years from the current annual price to earnings figure with today's closing price.