How much of the survey was re-flown

Counts lines that took more than one attempt, and reports the rate two ways because they are different numbers and the distinction matters.

Usage

reflight_summary(x)

Arguments

x

Point-level survey data, or a distsamp_segments; as line_effort().

Value

A one-row tibble: n_lines, n_occupations, n_lines_reflown, prop_lines_reflown, prop_occupations_repeat, effort_km, effort_km_repeat.

Two rates, deliberately both

Suppose ten occupations covered eight lines, because two lines were flown twice.

• prop_lines_reflown is 2/8 = 0.25 — a quarter of the lines needed a second attempt. This is what "what fraction of lines were re-flown" asks.

• prop_occupations_repeat is 2/10 = 0.20 — a fifth of the flying was a repeat of something already attempted. This is the one that bears on effort.

The scripts this package was rewritten from computed the second and labelled it the first (ds_data_dmr.R:229, carrying the comment "ask dan about this"). Both are reported here, named for what they measure, so neither can stand in for the other by accident.

See also

line_effort()

Examples

path <- system.file("extdata", "narwc-example.csv", package = "distsamp")
dat <- point_to_point_effort(flag_effort(make_leg_id(read_narwc(path))))
#> `read_narwc()` renamed 2 columns:
#>   LAT_DD  -> LATITUDE
#>   LONG_DD -> LONGITUDE
#> All matched an exact entry in the alias table; `narwc_column_mapping()` returns this, and `quiet = TRUE` silences it.
reflight_summary(dat)
#> # A tibble: 1 × 7
#>   n_lines n_occupations n_lines_reflown prop_lines_reflown
#>     <int>         <int>           <int>              <dbl>
#> 1       5             6               1                0.2
#> # ℹ 3 more variables: prop_occupations_repeat <dbl>, effort_km <dbl>,
#> #   effort_km_repeat <dbl>