# count_mu_phase1: Median of phase1 references In dscore: D-Score for Child Development

 count_mu_phase1 R Documentation

## Median of phase1 references

### Description

Returns the age-interpolated median of the phase1 references based on LF & SF in GSED-BGD, GSED-PAK, GSED-TZA.

### Usage

```count_mu_phase1(t)
```

### Arguments

 `t` Decimal age, numeric vector

### Details

The interpolation is done in two rounds. First round: Calculate D-scores using .gcdg prior-mean, calculate reference, estimate round 1 parameters used in this function. Round 2: Calculate D-score using round 1 estimates as the prior mean (most differences are within 0.1 D-score points), recalculate references, estimate round 2 parameters used in this function.

Round 1: Count model: <= 9MN: 21.3449 + 26.4916 t + 7.0251(t + 0.2) Count model: > 9Mn & <= 3.5 YR: 14.69947 - 12.18636 t + 69.11675(t + 0.92) Linear model: > 3.5 YRS: 61.40956 + 3.80904 t

Round 2: Count model: < 9MND: 20.5883 + 27.3376 t + 6.4254(t + 0.2) Count model: > 9MND & < 3.5 YR: 14.63748 - 12.11774 t + 69.05463(t + 0.92) Linear model: > 3.5 YRS: 61.37967 + 3.83513 t

The working range is 0-3.5 years. After the age of 3.5 years, the function will increase at an arbitrary rate of 3.8 D-score points per year. This function is intended to be called when `key = "gsed2212"`, `key = "gsed2208"` or `key = "293_0"`.

### Value

A vector of length `length(t)` with the median of the GCDG references.

### Note

Internal function. Called by `dscore()`

### Author(s)

Stef van Buuren, on behalf of GSED project

### Examples

```dscore:::count_mu_phase1(0:5)
```

dscore documentation built on Jan. 22, 2023, 1:50 a.m.