Package 'mitools'

Constructor for imputationList objects

Description

Create and update imputationList objects to be used as input to other MI routines.

Usage

imputationList(datasets,...)
## Default S3 method:
imputationList(datasets,...)
## S3 method for class 'character'
imputationList(datasets,dbtype,dbname,...)
## S3 method for class 'imputationList'
update(object,...)
## S3 method for class 'imputationList'
rbind(...)
## S3 method for class 'imputationList'
cbind(...)

Arguments

datasets	a list of data frames corresponding to the multiple imputations, or a list of names of database tables or views
dbtype	"ODBC" or a database driver name for DBI::dbDriver()
dbname	Name of the database
object	An object of class imputationList
...	Arguments tag=expr to update will create new variables tag by evaluating expr in each imputed dataset. Arguments to imputationList() are passed to the database driver

Details

When the arguments to imputationList() are character strings a database-based imputation list is created. This can be a database accessed through ODBC with the RODBC package or a database with a DBI-compatible driver. The dbname and ... arguments are passed to dbConnect() or odbcConnect() to create a database connection. Data are read from the database as needed.

For a database-backed object the update() method creates variable definitions that are evaluated as the data are read, so that read-only access to the database is sufficient.

Value

An object of class imputationList or DBimputationList

Examples

## Not run: 
## CRAN doesn't like this example
data.dir <- system.file("dta",package="mitools")
files.men <- list.files(data.dir,pattern="m.\\.dta$",full=TRUE)
men <- imputationList(lapply(files.men, foreign::read.dta))
files.women <- list.files(data.dir,pattern="f.\\.dta$",full=TRUE)
women <- imputationList(lapply(files.women, foreign::read.dta))
men <- update(men, sex=1)
women <- update(women,sex=0)
all <- rbind(men,women)
all <- update(all, drinkreg=as.numeric(drkfre)>2)
all

## End(Not run)

---

Multiple imputation inference

Description

Combines results of analyses on multiply imputed data sets. A generic function with methods for imputationResultList objects and a default method. In addition to point estimates and variances, MIcombine computes Rubin's degrees-of-freedom estimate and rate of missing information.

Usage

MIcombine(results, ...)
## Default S3 method:
MIcombine(results,variances,call=sys.call(),df.complete=Inf,...)
## S3 method for class 'imputationResultList'
MIcombine(results,call=NULL,df.complete=Inf,...)

Arguments

results	A list of results from inference on separate imputed datasets
variances	If results is a list of parameter vectors, variances should be the corresponding variance-covariance matrices
call	A function call for labelling the results
df.complete	Complete-data degrees of freedom
...	Other arguments, not used

Details

The results argument in the default method may be either a list of parameter vectors or a list of objects that have coef and vcov methods. In the former case a list of variance-covariance matrices must be supplied as the second argument.

The complete-data degrees of freedom are used when a complete-data analysis would use a t-distribution rather than a Normal distribution for confidence intervals, such as some survey applications.

Value

An object of class MIresult with summary and print methods

References

~put references to the literature/web site here ~

See Also

MIextract, with.imputationList

Examples

data(smi)
models<-with(smi, glm(drinkreg~wave*sex,family=binomial()))
summary(MIcombine(models))

betas<-MIextract(models,fun=coef)
vars<-MIextract(models, fun=vcov)
summary(MIcombine(betas,vars))

---

Extract a parameter from a list of results

Description

Used to extract parameter estimates and standard errors from lists produced by with.imputationList.

Usage

MIextract(results, expr, fun)

Arguments

results	A list of objects
expr	an expression
fun	a function of one argument

Details

If expr is supplied, it is evaluated in each element of results. Otherwise each element of results is passed as an argument to fun.

Value

A list

See Also

with.imputationList, MIcombine

Examples

data(smi)
models<-with(smi, glm(drinkreg~wave*sex,family=binomial()))

betas<-MIextract(models,fun=coef)
vars<-MIextract(models, fun=vcov)
summary(MIcombine(betas,vars))

---

Maths Performance Data from the PISA 2012 survey in New Zealand

Description

Data on maths performance, gender, some problem-solving variables and some school resource variables. This is actually a weighted survey: see withPV.survey.design in the survey package for a better analyis.

Usage

data("pisamaths")

Format

A data frame with 4291 observations on the following 26 variables.

SCHOOLID

School ID

CNT

Country id: a factor with levels New Zealand

STRATUM

a factor with levels NZL0101 NZL0102 NZL0202 NZL0203

OECD

Is the country in the OECD?

STIDSTD

Student ID

ST04Q01

Gender: a factor with levels Female Male

ST14Q02

Mother has university qualifications No Yes

ST18Q02

Father has university qualifications No Yes

MATHEFF

Mathematics Self-Efficacy: numeric vector

OPENPS

Mathematics Self-Efficacy: numeric vector

PV1MATH,PV2MATH,PV3MATH,PV4MATH,PV5MATH

'Plausible values' (multiple imputations) for maths performance

W_FSTUWT

Design weight for student

SC35Q02

Proportion of maths teachers with professional development in maths in past year

PCGIRLS

Proportion of girls at the school

PROPMA5A

Proportion of maths teachers with ISCED 5A (math major)

ABGMATH

Does the school group maths students: a factor with levels No ability grouping between any classes One of these forms of ability grouping between classes for s One of these forms of ability grouping for all classes

SMRATIO

Number of students per maths teacher

W_FSCHWT

Design weight for school

condwt

Design weight for student given school

Source

A subset extracted from the PISA2012lite R package, https://github.com/pbiecek/PISA2012lite

References

OECD (2013) PISA 2012 Assessment and Analytical Framework: Mathematics, Reading, Science, Problem Solving and Financial Literacy. OECD Publishing.

Examples

data(pisamaths)

means<-withPV(list(maths~PV1MATH+PV2MATH+PV3MATH+PV4MATH+PV5MATH), data=pisamaths,
       action= quote(by(maths, ST04Q01, mean)), rewrite=TRUE)
means

models<-withPV(list(maths~PV1MATH+PV2MATH+PV3MATH+PV4MATH+PV5MATH), data=pisamaths,
       action= quote(lm(maths~ST04Q01*PCGIRLS)), rewrite=TRUE)
summary(MIcombine(models))

---

Multiple imputations

Description

An imputationList object containing five imputations of data from the Victorian Adolescent Health Cohort Study.

Usage

data(smi)

Format

The underlying data are in a data frame with 1170 observations on the following 12 variables.

id

a numeric vector

wave

a numeric vector

mmetro

a numeric vector

parsmk

a numeric vector

drkfre

a factor with levels Non drinker not in last wk <3 days last wk >=3 days last wk

alcdos

a factor with levels Non drinker not in last wk av <5units/drink_day av =>5units/drink_day

alcdhi

a numeric vector

smk

a factor with levels non/ex-smoker <6 days 6/7 days

cistot

a numeric vector

mdrkfre

a numeric vector

sex

a numeric vector

drinkreg

a logical vector

Source

Carlin, JB, Li, N, Greenwood, P, Coffey, C. (2003) "Tools for analysing multiple imputed datasets" The Stata Journal 3; 3: 1-20.

Examples

data(smi)
with(smi, table(sex, drkfre))
model1<-with(smi, glm(drinkreg~wave*sex, family=binomial()))
MIcombine(model1)
summary(MIcombine(model1))

---

Evaluate an expression in multiple imputed datasets

Description

Performs a computation of each of imputed datasets in data

Usage

## S3 method for class 'imputationList'
with(data, expr, fun, ...)

Arguments

data	An imputationList object
expr	An expression
fun	A function taking a data frame argument
...	Other arguments, passed to fun

Details

If expr is supplied, evaluate it in each dataset in data; if fun is supplied, it is evaluated on each dataset. If all the results inherit from "imputationResult" the return value is an imputationResultList object, otherwise it is an ordinary list.

Value

Either a list or an imputationResultList object

See Also

imputationList

Examples

data(smi)
models<-with(smi, glm(drinkreg~wave*sex,family=binomial()))
tables<-with(smi, table(drkfre,sex))
with(smi, fun=summary)

---

Analyse plausible values in surveys

Description

Repeats an analysis for each of a set of 'plausible values' in a data set, returning a list suitable for MIcombine. That is, the data set contains some sets of columns where each set are multiple imputations of the same variable. With rewrite=TRUE, the action is rewritten to reference each plausible value in turn; with coderewrite=FALSE a new data set is constructed for each plausible value, which is slower but more general.

Usage

withPV(mapping, data, action, rewrite=TRUE, ...)
## Default S3 method:
withPV(mapping, data, action, rewrite=TRUE,...)

Arguments

mapping	A formula or list of formulas describing each variable in the analysis that has plausible values. The left-hand side of the formula is the name to use in the analysis; the right-hand side gives the names in the dataset.
data	A data frame. Methods for withPV dispatch on this argument, so can be written for, eg, survey designs or out-of-memory datasets.
action	With rewrite=TRUE, a quoted expression specifying the analysis, or a function taking a data frame as its only argument. With rewrite=FALSE, A function taking a data frame as its only argument, or a quoted expression with .DATA referring to the newly-created data frame to be used.
rewrite	Rewrite action before evaluating it (versus constructing new data sets)
...	For methods

Value

A list of the results returned by each evaluation of action, with the call as an attribute.

Note

I would be interested in seeing naturally-occurring examples where rewrite=TRUE does not work

See Also

pisamaths

with.imputationList

Examples

data(pisamaths)

models<-withPV(list(maths~PV1MATH+PV2MATH+PV3MATH+PV4MATH+PV5MATH), data=pisamaths,
       action= quote(lm(maths~ ST04Q01*(PCGIRLS+SMRATIO)+MATHEFF+OPENPS,
       data=.DATA)),
       rewrite=FALSE
)

summary(MIcombine(models))

## equivalently
models2<-withPV(list(maths~PV1MATH+PV2MATH+PV3MATH+PV4MATH+PV5MATH), data=pisamaths,
       action=quote( lm(maths~ST04Q01*(PCGIRLS+SMRATIO)+MATHEFF+OPENPS)), rewrite=TRUE)


summary(MIcombine(models2))

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