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Compute longitudinal change in LODES data across years

Source: R/compute_lodes_change.R
compute_lodes_change.Rd

Computes absolute and percentage change in LODES variables between two years for each geographic unit. This is particularly useful for tracking shifts in employment, industrial composition, or earnings structure over time.

Percentage change is computed as \((\text{compare} - \text{base}) / \text{base} \times 100\). Returns NA where base_value is zero or missing.

Usage

compute_lodes_change(
  lodes_df,
  geo_col = NULL,
  base_year = NULL,
  compare_year = NULL,
  variables = NULL,
  output = c("wide", "long")
)

Arguments

lodes_df

A data frame (tibble) of LODES data covering at least two years, as returned by grab_lodes() with a vector of years. Must contain a year column and one or more numeric columns to difference.

geo_col

The name of the geography column to group by, e.g. "w_tract", "h_county", or "w_geocode". Defaults to NULL, which auto-detects the first column ending in _geocode, _tract, _county, _bg, or _state.

base_year

The reference year for computing change. Defaults to the earliest year present in lodes_df.

compare_year

The target year for computing change. Defaults to the latest year present in lodes_df.

variables

Optional character vector of numeric column names to include in the output. Defaults to all numeric columns (excluding year).

output

One of "wide" (default) or "long". In wide format, absolute and percentage change columns are appended for each variable. In long format, each variable is a row with columns variable, base_value, compare_value, change, and pct_change.

Value

A tibble of change statistics. In "wide" format, columns follow the pattern {variable}_base, {variable}_compare, {variable}_change, and {variable}_pct_change. In "long" format, columns are variable, base_value, compare_value, change, and pct_change.

Examples

if (FALSE) { # \dontrun{
  wac_multi <- grab_lodes(
    state = "md", year = c(2015, 2019),
    lodes_type = "wac", job_type = "JT00",
    segment = "S000", agg_geo = "county"
  )
  compute_lodes_change(wac_multi, geo_col = "w_county")

  # Long format
  compute_lodes_change(
    wac_multi,
    geo_col  = "w_county",
    output   = "long",
    variables = c("C000", "CE01", "CE02", "CE03")
  )
} # }