Motivation: Our national source for Singapore reports GDP (expenditure approach), nominal total GDP at a quarterly frequency.  However, the nominal components are only available annually.  The source does not seasonally adjust nominal GDP data.

Response: For international consistency, we have created quarterly nominal GDP by component on a both seasonally adjusted and not seasonally adjusted basis.

Properties: Figures are in millions of nominal Singapore dollars (Mil. SGD) both seasonally adjusted (SA) and unadjusted (NSA). The 19 series begin at 1975Q1. Expect these series to be revised with each new update of the quarterly nominal GDP and/or updates to the annual nominal series. Two sample mnemonics are:
• NALEEXUQ.ISGP - Exports of goods and services, nominal
• NACEGFCFUQ.ISGP - Gross fixed capital formation, nominal

Method:

1. Create an initial estimate of implicit price deflators (IPD) for GDP components.
   • Calculate annual IPD by dividing the annual nominal series by the quarterly constant series.
   • Convert the annual IPDs into a quarterly series by applying the quarterly pattern from the not seasonally adjusted implicit price deflator for total GDP (NAIGDPMPUQ.ISGP) reported by the National Statistical Office.
   • Extend the quarterly IPDs using the growth rate from quarterly total GDP IPD (NAIGDPMPUQ.ISGP).
2. Calculate quarterly nominal not seasonally adjusted GDP components by applying quarterly IPDs created in Step #1 to quarterly not seasonally adjusted constant dollar GDP components provide by the National Statistical Office (SingStat).  Ensure that the quarterly values average to the reported annual nominal values.
3. Seasonally adjust the quarterly nominal GDP components using the U.S. Census Bureau's X-12 ARIMA program and annualize the series by multiplying by 4.
4. Compute identities:
   • Calculate seasonally adjusted quarterly implicit price deflators for GDP component by dividing quarterly seasonally adjusted nominal GDP by quarterly seasonally adjusted real GDP.
   • Calculate the not seasonally adjusted nominal statistical discrepancy as the residual of quarterly not seasonally adjusted nominal total GDP (NALEGDPUQ.ISGP) – quarterly not seasonally adjusted nominal components of GDP except statistical discrepancy.
   • Assume no seasonality in statistical discrepancy and make seasonally adjusted nominal statistical discrepancy (RNALESDAQ.ISGP) = not seasonally adjusted nominal statistical discrepancy (RNALESDUQ.ISGP).
   • Calculate nominal quarterly seasonally adjusted total GDP (RNALEGDPAQ.ISGP) as an aggregate of nominal quarterly seasonally adjusted components of GDP.