Red flag: NSO's 2003 Master Sample

The sad fact is that the samples of Philippine household surveys (such as the FIES, LFS, APIS, NDHS) before and after 2003 are non-comparable. This is because of the reconstruction of NSO's master sample in 2003 owing to the results of the 2000 Census of Population and Housing (here is a brochure; here is a detailed paper). Thus, be careful when choosing your sample years especially when you intend to follow/trace households over time.