NeEDS4BigData (version 1.0.1)

modelMissLinSub: Subsampling under linear regression for a potentially misspecified model

Description

Using this function sample from big data under linear regression for a potentially misspecified model. Subsampling probabilities are obtained based on the A-, L- and L1- optimality criteria with the RLmAMSE (Reduction of Loss by minimizing the Average Mean Squared Error).

Usage

modelMissLinSub(r0,rf,Y,X,N,Alpha,proportion,model="Auto")

Value

The output of modelMissLinSub gives a list of

Beta_Estimates estimated model parameters after subsampling

Variance_Epsilon_Estimates matrix of estimated variance for epsilon after subsampling

Utility_Estimates estimated A-, L- and L1- optimality values for the obtained subsamples

AMSE_Estimates matrix of estimated AMSE values after subsampling

Sample_A-Optimality list of indexes for the initial and optimal samples obtained based on A-Optimality criteria

Sample_L-Optimality list of indexes for the initial and optimal samples obtained based on L-Optimality criteria

Sample_L1-Optimality list of indexes for the initial and optimal samples obtained based on L1-Optimality criteria

Sample_RLmAMSE list of indexes for the optimal samples obtained based obtained based on RLmAMSE

Sample_RLmAMSE_Log_Odds list of indexes for the optimal samples obtained based on RLmAMSE with Log Odds function

Sample_RLmAMSE_Power list of indexes for the optimal samples obtained based on RLmAMSE with Power function

Subsampling_Probability matrix of calculated subsampling probabilities

Arguments

r0

sample size for initial random sample

rf

final sample size including initial(r0) and optimal(r) samples

Y

response data or Y

X

covariate data or X matrix that has all the covariates (first column is for the intercept)

N

size of the big data

Alpha

scaling factor when using Log Odds or Power functions to magnify the probabilities

proportion

a proportion of the big data is used to help estimate AMSE values from the subsamples

model

formula for the model used in the GAM or the default choice

Details

The article for this function is in preparation for publication. Please be patient.

Two stage subsampling algorithm for big data under linear regression for potential model misspecification.

First stage is to obtain a random sample of size \(r_0\) and estimate the model parameters. Using the estimated parameters subsampling probabilities are evaluated for A-, L-, L1-optimality criteria, RLmAMSE and enhanced RLmAMSE (log-odds and power) subsampling methods.

Through the estimated subsampling probabilities a sample of size \(r \ge r_0\) is obtained. Finally, the two samples are combined and the model parameters are estimated for A-, L-, L1-optimality, RLmAMSE and enhanced RLmAMSE (log-odds and power).

NOTE : If input parameters are not in given domain conditions necessary error messages will be provided to go further.

If \(r \ge r_0\) is not satisfied then an error message will be produced.

If the big data \(X,Y\) has any missing values then an error message will be produced.

The big data size \(N\) is compared with the sizes of \(X,Y\),F_estimate_Full and if they are not aligned an error message will be produced.

If \(\alpha > 1\) for the scaling factor is not satisfied an error message will be produced.

If proportion is not in the region of \((0,1]\) an error message will be produced.

model is a formula input formed based on the covariates through the spline terms (s()), squared term (I()), interaction terms (lo()) or automatically. If model is empty or NA or NAN or not one of the defined inputs an error message is printed. As a default we have set model="Auto", which is the main effects model wit the spline terms.

References

adewale2009robustNeEDS4BigData

adewale2010robustNeEDS4BigData

Amalan2025MisspecificationNeEDS4BigData

Examples

Beta <- c(-1, 0.75, 0.75, 1); Var_Epsilon <- 0.5;
family <- "linear"; N <- 500
X_1 <- replicate(2, stats::runif(n = N, min = -1, max = 1))

Temp <- Rfast::rowprods(X_1)
Misspecification <- (Temp - mean(Temp)) / sqrt(mean(Temp^2) - mean(Temp)^2)
X_Data <- cbind(X0 = 1, X_1)

Full_Data <- GenModelMissGLMdata(N, X_Data, Misspecification, Beta, Var_Epsilon, family)
r0 <- 40; rf <- rep(10 * c(8, 12), 25)
Original_Data <- Full_Data$Complete_Data[, -ncol(Full_Data$Complete_Data)]

Results <- modelMissLinSub(r0 = r0, rf = rf,
                           Y = as.matrix(Original_Data[, 1]),
                           X = as.matrix(Original_Data[, -1]),
                           N = N, Alpha = 10, proportion = 0.5)

plot_Beta(Results)
plot_AMSE(Results)