With the Ratios feature, you can have most series as divided by GDP or population in your Series list by a simple click of a button if defined variables exist for the corresponding country.

If you want to see underlying calculation behind the ratio, go to the *Series information* tab in Series list, right click on the series and select “View calculations”. This will open a new tab in Analytics with a snapshot of the calculated series document that was created by the macro language. You have the option to save this as a real calculated in-house series if you like.

Below you’ll find information on the methodology used by Macrobond in the background when calculating these ratios.

# PerCapita

- Macrobond uses the series of the variable that has the same frequency as the nominator, where the source is indicated. If there is no match, it uses a series with the closest higher frequency. If there is no match neither, as a last resort, it uses a series with the closest lower frequency.
- If the series from point 1) has shorter history than the numerator, Macrobond looks for all the series with longer history. If any of them can be found, Macrobond uses the one closest in frequency (higher frequency is preferred) and extends the series from point 1) using the formula function
`JoinMoreHistoryScaled`. - If the series from point 1) covers more future observations than the numerator, Macrobond looks for all series that covers more future observations. If any of them can be found, Macrobond uses the one closest in frequency (higher frequency is preferred) and extends the series from point 2) using the formula function
`JoinScaledAppend`. - For the denominator, Macrobond sets the frequency conversion to
*Interpolate*and sets the Partial period method to*Rate of change*.

# PerGDP & PerGDPPercent

- First, Macrobond tries to find a series that has the same or higher frequency from the source. If this is not available, a lower frequency is used.
- Macrobond tries to match the seasonality of the numerator from the database. If the numerator is seasonally adjusted, but there is no adjusted series from the source, it seasonally adjusts the denominator. If the numerator is not seasonally adjusted, but the source only offers adjusted series, Macrobond seasonally adjust the numerator.
- If the numerator is a flow series, Macrobond converts it from annual rate in case they are of different frequency or if only one of them is expressed in this way.
- If the numerator is not a flow series, Macrobond annualizes the denominator, if it is not already in annual rate, by multiplying by the number of observations per year.
- When doing seasonal adjustments, the Seasonal adjustment Census X-13 analysis is used if the series is quarterly or monthly. If the series is annual, Macrobond does not add any seasonal adjustment. In all other cases the Moving Average version of the seasonal adjustment is used.
- If the GDP series ends earlier than the numerator, the formula function
`ExtendLastYoYForecast`is used to extend the series. - Finally, the numerator is converted to the same currency as the denominator.
- The
**PerGDPPercent**version follows the same methodology, but the result is then multiplied by 100 and the unit is set to “percent”.

# PerCPI, PerCPICore & PerCPIHarmonized

*Per CPI, Per CPI Core and Per CPI Harmonized options are available in Macrobond 1.21 and later.*

- First, Macrobond tries to find a series that has the same or higher frequency from the source. If this is not available, a lower frequency is used.
- Macrobond tries to match the seasonality of the numerator from the database. If the numerator is seasonally adjusted, but there is no adjusted series from the source, it seasonally adjusts the denominator. If the numerator is not seasonally adjusted, but the source only offers adjusted series, Macrobond seasonally adjust the numerator.
- When doing seasonal adjustments, the Seasonal adjustment Census X-13 analysis is used if the series is quarterly or monthly. If the series is annual, Macrobond does not add any seasonal adjustment. In all other cases the Moving Average version of the seasonal adjustment is used.
- When the price index series is chosen and seasonally adjusted (if applicable), the price index series is divided by ‘100’.
- There are no limitations to what series that can be divided by the price denominators, even data published in real, volume, terms can be divided by these ratios.
- If the frequency of the numerator is lower, the price index series is averaged. If the frequency is higher, the price index series is linearly interpolated.

### Additional settings used

- “Extend partial periods” setting is always set to automatic for the denominator series.
- The frequency of the calculation is set to that of the numerator.
- Annual rate is removed in case series are of different frequency or if only one of them is expressed in this way.
- The result should not be associated with any currency.