The get_reference() function selects the D-score reference
distribution.
get_reference(
population = NULL,
key = NULL,
references = dscore::builtin_references,
verbose = FALSE,
...
)String. The name of the reference population to calculate
DAZ.
Use with(builtin_references, table(key, population)) to see which
built-in references are available for key - population combinations.
If not specified, the function set the default population as
builtin_keys$base_population[key == builtin_keys$key].
String. They key identifies 1) the difficulty estimates
pertaining to a particular Rasch model, and 2) the prior mean and standard
deviation of the prior distribution for calculating the D-score.
The default key NULL sets key = "gsed2406".
View builtin_keys for an overview of the available keys.
A data.frame with the same structure as builtin_references.
The default is to use builtin_references.
Logical. Print settings.
Used to test whether the call contained the deprecated argument
references.
A data.frame with the LMS reference values.
No references for population "gsed" exist.
The function will silently rewrite population = "gsed"
into to the population = "gsed".
The "dutch" reference was published in Van Buuren (2014)
The "gcdg" was calculated from 15 cohorts with direct
observations (Weber, 2019).
The "phase1" references were calculated from the GSED Phase 1 validation
data (GSED-BGD, GSED-PAK, GSED-TZA) cover age range 2w-3.5 years. The
age range 3.5-5 yrs is linearly extrapolated and are only indicative.
The "preliminary_standards" references were calculated from the GSED
Phase 1 validation using a subset of children with healthy development.
Van Buuren S (2014). Growth charts of human development. Stat Methods Med Res, 23(4), 346-368.
Weber AM, Rubio-Codina M, Walker SP, van Buuren S, Eekhout I, Grantham-McGregor S, Caridad Araujo M, Chang SM, Fernald LCH, Hamadani JD, Hanlon A, Karam SM, Lozoff B, Ratsifandrihamanana L, Richter L, Black MM (2019). The D-score: a metric for interpreting the early development of infants and toddlers across global settings. BMJ Global Health, BMJ Global Health 4: e001724. https://gh.bmj.com/content/bmjgh/4/6/e001724.full.pdf.
# see key-population combinations of builtin_references
table(builtin_references$key, builtin_references$population)
#>
#> dutch gcdg phase1 preliminary_standards
#> 293_0 0 0 186 0
#> dutch 144 0 0 0
#> gcdg 0 121 0 0
#> gsed1912 0 121 0 0
#> gsed2212 185 0 186 0
#> gsed2406 185 0 186 185
# get the default reference
reftab <- get_reference()
head(reftab, 2)
#> population key distribution age mu sigma nu
#> 944 preliminary_standards gsed2406 BCT 0.0383 13.18 0.2075 1.420
#> 945 preliminary_standards gsed2406 BCT 0.0575 14.04 0.2001 1.426
#> tau P3 P10 P25 P50 P75 P90 P97
#> 944 34.189 7.283800 9.373415 11.26089 13.18304 14.99519 16.57957 18.13494
#> 945 34.121 7.991835 10.132744 12.06843 14.04231 15.90526 17.53530 19.13639
#> SDM2 SDM1 SD0 SDP1 SDP2
#> 944 6.833076 10.27212 13.18304 15.84778 18.44597
#> 945 7.529790 11.05407 14.04231 16.78229 19.45665
# get the default reference for the key "gsed2212"
reftab <- get_reference(key = "gsed2212", verbose = TRUE)
#> key: gsed2212
#> population: phase1
# get dutch reference for default key
reftab <- get_reference(population = "dutch", verbose = TRUE)
#> key: gsed2406
#> population: dutch
# loading a non-existing reference yields zero rows
reftab <- get_reference(population = "france", verbose = TRUE)
#> key: gsed2406
#> population: france
#> Warning: Reference 'france' for key 'gsed2406' not found. Using default.
nrow(reftab)
#> [1] 185