# Obtain the Horvitz-Thompson direct estimates and standard errors using delta method for a single survey.

Source:`R/countrySummary.R`

`getDirect.Rd`

Obtain the Horvitz-Thompson direct estimates and standard errors using delta method for a single survey.

## Usage

```
getDirect(
births,
years,
regionVar = "region",
timeVar = "time",
clusterVar = "~v001+v002",
ageVar = "age",
weightsVar = "v005",
Ntrials = NULL,
geo.recode = NULL,
national.only = FALSE,
CI = 0.95
)
```

## Arguments

- births
A matrix child-month data from

`getBirths`

- years
String vector of the year intervals used

- regionVar
Variable name for region in the input births data.

- timeVar
Variable name for the time period indicator in the input births data.

- clusterVar
Variable name for cluster, typically '~v001 + v002'

- ageVar
Variable name for age group. This variable need to be in the form of "a-b" where a and b are both ages in months. For example, "1-11" means age between 1 and 11 months, including both end points. An exception is age less than one month can be represented by "0" or "0-0".

- weightsVar
Variable name for sampling weights, typically 'v005'

- Ntrials
Variable for the total number of person-months if the input data (births) is in the compact form.

- geo.recode
The recode matrix to be used if region name is not consistent across different surveys. See

`ChangeRegion`

.- national.only
Logical indicator to obtain only the national estimates

- CI
the desired confidence interval to calculate

## Value

a matrix of period-region summary of the Horvitz-Thompson direct estimates by region and time period specified in the argument, the standard errors using delta method for a single survey, the 95% confidence interval, and the logit of the estimates.

## References

Li, Z., Hsiao, Y., Godwin, J., Martin, B. D., Wakefield, J., Clark, S. J., & with support from the United Nations Inter-agency Group for Child Mortality Estimation and its technical advisory group. (2019). *Changes in the spatial distribution of the under-five mortality rate: Small-area analysis of 122 DHS surveys in 262 subregions of 35 countries in Africa.* PloS one, 14(1), e0210645.

Mercer, L. D., Wakefield, J., Pantazis, A., Lutambi, A. M., Masanja, H., & Clark, S. (2015). *Space-time smoothing of complex survey data: small area estimation for child mortality.* The annals of applied statistics, 9(4), 1889.