pnadc_identify_periods: Identify Reference Periods in PNADC Data

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

Identify Reference Periods in PNADC Data

Description

PNADC is a quarterly survey, but each interview actually refers to a specific temporal period within the quarter. This function identifies which month, fortnight (quinzena), and week each observation belongs to, enabling sub-quarterly time series analysis.

The algorithm uses a nested identification approach:

• Phase 1: Identify MONTHS for all observations using:

  • IBGE's reference week timing rules (first reference week – ending in a Saturday – with sufficient days)

  • Respondent birthdates to constrain possible interview dates

  • UPA-panel level aggregation across ALL quarters (panel design)

  • Dynamic exception detection (identifies quarters needing relaxed rules)

• Phase 2: Identify FORTNIGHTS for month-determined observations:

  • Search space constrained to 2 fortnights within determined month

  • Household-level aggregation within each quarter

• Phase 3: Identify WEEKS for fortnight-determined observations:

  • Search space constrained to ~2 weeks within determined fortnight

  • Household-level aggregation within each quarter

Usage

pnadc_identify_periods(data, verbose = TRUE, store_date_bounds = FALSE)

Arguments

data	A data.frame or data.table with PNADC microdata. Required columns: Ano: Survey year Trimestre: Quarter (1-4) UPA: Primary Sampling Unit V1008: Household id/sequence within UPA V1014: Panel identifier V2008: Birth day (1-31) V20081: Birth month (1-12) V20082: Birth year V2009: Age Optional but recommended: V2003: Person sequence within household
verbose	Logical. If TRUE (default), display progress information.
store_date_bounds	Logical. If TRUE, stores date bounds and exception flags in the crosswalk for optimization when calling pnadc_experimental_periods(). This enables 10-20x speedup for the probabilistic strategy by avoiding redundant computation. Default FALSE.

Details

Builds a crosswalk containing reference periods (month, fortnight, and week) for PNADC survey data based on IBGE's interview timing rules.

Temporal Granularity

The crosswalk contains three levels of temporal granularity:

• Month: 3 per quarter, ~97\

• Fortnight (quinzena): 6 per quarter, ~9\

• Week: 12 per quarter, ~3\

Cross-Quarter Aggregation (Important!)

For optimal month determination rates, input data should be stacked across multiple quarters (ideally 4+ years). The algorithm leverages PNADC's rotating panel design where the same UPA-V1014 is interviewed in the same relative position across quarterly visits.

Fortnight Definition

Fortnights are numbered 1-6 per quarter (2 per month), based on the IBGE reference week calendar (not calendar days). Each IBGE "month" consists of exactly 4 reference weeks (28 days), starting on a Sunday:

• Fortnight 1 in month: IBGE weeks 1-2 (days 1-14 of the IBGE month)

• Fortnight 2 in month: IBGE weeks 3-4 (days 15-28 of the IBGE month)

Value

A data.table crosswalk with columns:

Ano, Trimestre, UPA, V1008, V1014

Join keys (year, quarter, UPA, household, panel)

ref_month_in_quarter

Integer. Month position in quarter (1, 2, 3) or NA

ref_month_in_year

Integer. Month position in year (1-12) or NA

ref_fortnight_in_month

Integer. Fortnight position in month (1 or 2) or NA

ref_fortnight_in_quarter

Integer. Fortnight position in quarter (1-6) or NA

ref_week_in_month

Integer. Week position in month (1-4) or NA

ref_week_in_quarter

Integer. Week position in quarter (1-12) or NA

date_min

Date. Lower bound of the interview reference date for the individual. Only returned if store_date_bounds = TRUE

date_max

Date. Upper bound of the interview reference date for the individual. Only returned if store_date_bounds = TRUE

week_1_start

Date. Sunday of the IBGE first reference week of the month. Only returned if store_date_bounds = TRUE

week_1_end

Date. Saturday of the IBGE first reference week of the month. Only returned if store_date_bounds = TRUE

week_2_start

Date. Sunday of the IBGE second reference week of the month. Only returned if store_date_bounds = TRUE

week_2_end

Date. Saturday of the IBGE second reference week of the month. Only returned if store_date_bounds = TRUE

week_3_start

Date. Sunday of the IBGE third reference week of the month. Only returned if store_date_bounds = TRUE

week_3_end

Date. Saturday of the IBGE third reference week of the month. Only returned if store_date_bounds = TRUE

week_4_start

Date. Sunday of the IBGE fourth reference week of the month. Only returned if store_date_bounds = TRUE

week_4_end

Date. Saturday of the IBGE fourth reference week of the month. Only returned if store_date_bounds = TRUE

month_max_upa

Integer. Maximum month position across UPA-V1014 group (for debugging). Only returned if store_date_bounds = TRUE

month_min_upa

Integer. Minimum month position across UPA-V1014 group (for debugging). Only returned if store_date_bounds = TRUE

fortnight_max_hh

Integer. Maximum fortnight position within household (for debugging). Only returned if store_date_bounds = TRUE

fortnight_min_hh

Integer. Minimum fortnight position within household (for debugging). Only returned if store_date_bounds = TRUE

week_min_hh

Integer. Minimum week position within household (for debugging). Only returned if store_date_bounds = TRUE

week_max_hh

Integer. Maximum week position within household (for debugging). Only returned if store_date_bounds = TRUE

ref_month_yyyymm

Integer. Identified reference month in the format YYYYMM, where MM follows the IBGE calendar. 1 <= MM <= 12

ref_fortnight_yyyyff

Integer. Identified reference fortnight in the format YYYYFF, where FF follows the IBGE calendar. 1 <= FF <= 24

ref_week_yyyyww

Integer. Identified reference Week in the format YYYYWW, where WW follows the IBGE calendar. 1 <= WW <= 48

determined_month

Logical. Flags if the month was determined.

determined_fortnight

Logical. Flags if the fortnight was determined.

determined_week

Logical. Flags if the week was determined.

Note

Nested Identification Hierarchy

The algorithm enforces strict nesting by construction:

• Fortnights can ONLY be identified for observations with determined months

• Weeks can ONLY be identified for observations with determined fortnights

This guarantees: determined_week => determined_fortnight => determined_month

Aggregation Levels

The crosswalk aggregates at different levels:

• Months: UPA-V1014 level across ALL quarters (PNADC panel design ensures same month position)

• Fortnights: Household level within quarter only

• Weeks: Household level within quarter only

See Also

pnadc_apply_periods to apply the crosswalk and calibrate weights

Examples

## Not run: 
crosswalk <- pnadc_identify_periods(pnadc_stacked)

crosswalk[, .(
  month_rate = mean(determined_month),
  fortnight_rate = mean(determined_fortnight),
  week_rate = mean(determined_week)
)]

crosswalk[determined_fortnight, all(determined_month)]
crosswalk[determined_week, all(determined_fortnight)]

result <- pnadc_apply_periods(pnadc_2023, crosswalk,
                              weight_var = "V1028",
                              anchor = "quarter")

## End(Not run)

PNADCperiods documentation built on April 28, 2026, 9:07 a.m.