PNADCperiods: Identify Reference Periods in Brazil's PNADC Survey Data

The PNADCperiods package provides tools to identify the exact reference period (month, fortnight, or week) of Brazil's quarterly official household survey, PNADC (Pesquisa Nacional por Amostra de Domicilios Continua - IBGE), allowing for analyzing the survey data at sub-quarterly temporal granularity.

Details

The package offers four main capabilities:

1. Reference period identification: Determines which temporal period (month, fortnight, or week) within each quarter each survey observation refers to, using IBGE's "Parada Técnica" rules and respondent birthdates. The identification is nested by construction: fortnights require months, and weeks require fortnights.

2. Period-specific weight calibration: Adjusts survey weights for sub-quarterly estimates using adaptive hierarchical rake weighting (4/2/1 cell levels for month/fortnight/week respectively)

3. Experimental strategies: Probabilistic assignment and UPA aggregation to boost fortnight/week determination rates for sensitivity analysis

4. SIDRA series mensalization: Converts IBGE's rolling quarterly (trimestre móvel) aggregate series to exact monthly estimates

Determination rates (strict, full series 2012-2025):

• Monthly: ~97\

• Fortnight: ~9\

• Week: ~3\

With smaller datasets, rates may differ (e.g., 8 quarters: ~94\ Experimental strategies (probabilistic + UPA aggregation) further improve these determination rates.

The package is highly optimized for large datasets (~450,000 rows/sec). Uses pre-computed lookup tables for 20x faster date creation.

Note: Strict fortnight and week determination rates are inherently low because they cannot leverage cross-quarter aggregation like months can. Only birthday constraints within a single quarter are available to narrow the interview window.

The main functions are:

• pnadc_identify_periods: Builds a crosswalk containing month, fortnight, and week reference periods with IBGE calendar-based dates

• pnadc_apply_periods: Applies the crosswalk to any PNADC dataset and optionally calibrates weights

• pnadc_experimental_periods: Applies experimental strategies (probabilistic, UPA aggregation) for improved fortnight/week determination

• get_sidra_series_metadata: Lists 86+ available PNADC rolling quarter series from SIDRA

• fetch_sidra_rolling_quarters: Downloads rolling quarterly data from IBGE SIDRA API

• mensalize_sidra_series: Converts rolling quarters to exact monthly estimates

References

HECKSHER, Marcos. "Valor Impreciso por Mes Exato: Microdados e Indicadores Mensais Baseados na Pnad Continua". IPEA - Nota Tecnica Disoc, n. 62. Brasilia, DF: IPEA, 2020. https://portalantigo.ipea.gov.br/portal/index.php?option=com_content&view=article&id=35453

HECKSHER, M. "Cinco meses de perdas de empregos e simulacao de um incentivo a contratacoes". IPEA - Nota Tecnica Disoc, n. 87. Brasilia, DF: IPEA, 2020.

HECKSHER, Marcos. "Mercado de trabalho: A queda da segunda quinzena de marco, aprofundada em abril". IPEA - Carta de Conjuntura, v. 47, p. 1-6, 2020.

IBGE. Manual Basico da Entrevista PNADC (methodology on "Parada Tecnica").

See also

Useful links:

• https://antrologos.github.io/PNADCperiods/

• https://github.com/antrologos/PNADCperiods

• Report bugs at https://github.com/antrologos/PNADCperiods/issues

Author

Rogerio Barbosa rogerio.barbosa@iesp.uerj.br (R package, dashboard, and website; Ceres-IESP/UERJ)

Marcos Hecksher mdhecksher@gmail.com (mensalization methodology; Ipea)