Last updated: 2018-05-17

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Algorithm

Let \(X_t\) be a Binomial observation with number of trials \(n_t\), \(t=1,2,\dots,T\).

  1. Apply ash to binomial data \((X_t, n_t)\) and obtain the posterior mean \(\hat p=E(p|X,n)\), \(\hat p\in R^T\).
  2. Let \(s_t=\frac{1}{n_t\hat p_t(1-\hat p_t)}\) and \(Y_t=\log\frac{\hat p_t}{1-\hat p_t}+\frac{X_t/n_t-\hat p_t}{n_t\hat p_t(1-\hat p_t)}\).
  3. Apply smash.gaus to \(Y_t\) with standard deviation \(\sqrt(\sigma^2+s_t^2)\) if \(\sigma^2\) is known. If it’s unknown, then either \(\sigma^2\) or \(\sigma^2+s_t^2\) should be estimated first. The output of smash.gaus is denoted as \(\mu_t\).
  4. Export \(\frac{\exp(\mu_t)}{1+\exp(\mu_t)}\).

Methods for estimating \(\sigma^2\) or \(\sigma^2+s_t^2\) are discussed here.

library(smashrgen)
library(ggplot2)
simu_study=function(p,sigma,ntri,nsimu=100,seed=12345,
                    niter=1,family='DaubExPhase',ashp=TRUE,verbose=FALSE,robust=FALSE,
                    tol=1e-2){
  set.seed(seed)
  #smash.err=c()
  smashgen.err=c()
  smashgen.smashu.err=c()
  #smashgen.mle.err=c()
  n=length(p)
  true.p=exp(p)/(1+exp(p))
  for(k in 1:nsimu){
    ng=rnorm(n,0,sigma)
    m=exp(p+ng)
    q=m/(1+m)
    x=rbinom(n,ntri,q)
    #fit data
    #smash.out=smash.poiss(x)
    smashgen.out=smash_gen(x,dist_family = 'binomial',sigma = sigma,ntri=ntri)
    smashu.out=smash_gen(x,dist_family = 'binomial',y_var_est = 'smashu',ntri=ntri)
    #mle.out=smash_gen(x,dist_family = 'poisson',y_var_est = 'mle')
    #smash.err[k]=mse(exp(m),smash.out)
    smashgen.err[k]=mse(true.p,smashgen.out)
    smashgen.smashu.err[k]=mse(true.p,smashu.out)
    #smashgen.mle.err[k]=mse(exp(m),mle.out)
  }
  return(list(est=list(smashgen.out=smashgen.out,smashu.out=smashu.out,x=x),err=data.frame(smashgen=smashgen.err, smashgen.smashu=smashgen.smashu.err)))
}

Constant trend

\(\sigma=0.1\)

p=rep(0,128)
set.seed(111)
ntri=rpois(128,30)
result=simu_study(p,0.1,ntri)
par(mfrow=c(1,2))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: known variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashgen.out,col=4)
legend("topright", # places a legend at the appropriate place
       c("truth","smashgen"), # puts text in the legend
       lty=c(1,1), # gives the legend appropriate symbols (lines)
       lwd=c(1,1),
       cex = 1,
       col=c("black","blue"))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: unknown variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashu.out,col=4)
legend("topright", # places a legend at the appropriate place
       c("truth","smashgen"), # puts text in the legend
       lty=c(1,1), # gives the legend appropriate symbols (lines)
       lwd=c(1,1),
       cex = 1,
       col=c("black","blue"))

mean(result$err$smashgen)
[1] 8.957221e-05
mean(result$err$smashgen.smashu)
[1] 9.913624e-05
ggplot(df2gg(result$err),aes(x=method,y=MSE))+geom_boxplot(aes(fill=method))+labs(x='')

\(\sigma=1\)

result=simu_study(p,1,ntri)
par(mfrow=c(1,2))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: known variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashgen.out,col=4)
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: unknown variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashu.out,col=4)

mean(result$err$smashgen)
[1] 0.0007841879
mean(result$err$smashgen.smashu)
[1] 0.0008206814
ggplot(df2gg(result$err),aes(x=method,y=MSE))+geom_boxplot(aes(fill=method))+labs(x='')

\(\sigma=1\), small prob

p=rep(-3,128)
result=simu_study(p,1,ntri)
par(mfrow=c(1,2))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: known variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashgen.out,col=4)
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: unknown variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashu.out,col=4)

mean(result$err$smashgen)
[1] 2.175465e-05
mean(result$err$smashgen.smashu)
[1] 2.726665e-05
ggplot(df2gg(result$err),aes(x=method,y=MSE))+geom_boxplot(aes(fill=method))+labs(x='')

Step trend

\(\sigma=0.1\)

p=c(rep(-2,128), rep(0, 128), rep(2, 128), rep(-2, 128))
set.seed(111)
ntri=rpois(512,30)
result=simu_study(p,0.1,ntri)

par(mfrow=c(1,2))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: known variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashgen.out,col=4)
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: unknown variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashu.out,col=4)

mean(result$err$smashgen)
[1] 0.0003595882
mean(result$err$smashgen.smashu)
[1] 0.0004350061
ggplot(df2gg(result$err),aes(x=method,y=MSE))+geom_boxplot(aes(fill=method))+labs(x='')

\(\sigma=1\)

p=c(rep(-2,128), rep(0, 128), rep(2, 128), rep(-2, 128))
set.seed(111)
ntri=rpois(512,30)
result=simu_study(p,1,ntri)

par(mfrow=c(1,2))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: known variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashgen.out,col=4)
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: unknown variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashu.out,col=4)

mean(result$err$smashgen)
[1] 0.001850991
mean(result$err$smashgen.smashu)
[1] 0.001842285
ggplot(df2gg(result$err),aes(x=method,y=MSE))+geom_boxplot(aes(fill=method))+labs(x='')

\(\sigma=1\), more variant ntri

p=c(rep(-2,128), rep(0, 128), rep(2, 128), rep(-2, 128))
set.seed(111)
ntri=rpois(512,50)-20
result=simu_study(p,1,ntri)

par(mfrow=c(1,2))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: known variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashgen.out,col=4)
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: unknown variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashu.out,col=4)

mean(result$err$smashgen)
[1] 0.001875976
mean(result$err$smashgen.smashu)
[1] 0.001847042
ggplot(df2gg(result$err),aes(x=method,y=MSE))+geom_boxplot(aes(fill=method))+labs(x='')

Bumps

\(\sigma=0.1\)

m=seq(0,1,length.out = 256)
h = c(4, 5, 3, 4, 5, 4.2, 2.1, 4.3, 3.1, 5.1, 4.2)
w = c(0.005, 0.005, 0.006, 0.01, 0.01, 0.03, 0.01, 0.01, 0.005,0.008,0.005)
t=c(.1,.13,.15,.23,.25,.4,.44,.65,.76,.78,.81)
f = c()
for(i in 1:length(m)){
  f[i]=sum(h*(1+((m[i]-t)/w)^4)^(-1))
}
p=f-3

set.seed(111)
ntri=rpois(256,30)
result=simu_study(p,0.1,ntri)

par(mfrow=c(1,2))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: known variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashgen.out,col=4)
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: unknown variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashu.out,col=4)

mean(result$err$smashgen)
[1] 0.001821751
mean(result$err$smashgen.smashu)
[1] 0.005024706
ggplot(df2gg(result$err),aes(x=method,y=MSE))+geom_boxplot(aes(fill=method))+labs(x='')

\(\sigma=1\)

set.seed(111)
ntri=rpois(256,30)
result=simu_study(p,1,ntri)

par(mfrow=c(1,2))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: known variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashgen.out,col=4)
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: unknown variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashu.out,col=4)

mean(result$err$smashgen)
[1] 0.0124867
mean(result$err$smashgen.smashu)
[1] 0.01233137
ggplot(df2gg(result$err),aes(x=method,y=MSE))+geom_boxplot(aes(fill=method))+labs(x='')

\(\sigma=1\), more variant ntri

set.seed(111)
ntri=rpois(256,50)-20
result=simu_study(p,1,ntri)

par(mfrow=c(1,2))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: known variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashgen.out,col=4)
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: unknown variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashu.out,col=4)

mean(result$err$smashgen)
[1] 0.01249222
mean(result$err$smashgen.smashu)
[1] 0.01226534
ggplot(df2gg(result$err),aes(x=method,y=MSE))+geom_boxplot(aes(fill=method))+labs(x='')

\(\sigma=1\), smaller ntri

set.seed(111)
ntri=rpois(256,20)-9
result=simu_study(p,1,ntri)

par(mfrow=c(1,2))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: known variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashgen.out,col=4)
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: unknown variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashu.out,col=4)

mean(result$err$smashgen)
[1] 0.02209255
mean(result$err$smashgen.smashu)
[1] 0.01565017
ggplot(df2gg(result$err),aes(x=method,y=MSE))+geom_boxplot(aes(fill=method))+labs(x='')

Spike mean

\(\sigma=0.1\)

spike.f = function(x) (0.75 * exp(-500 * (x - 0.23)^2) + 1.5 * exp(-2000 * (x - 0.33)^2) + 3 * exp(-8000 * (x - 0.47)^2) + 2.25 * exp(-16000 * 
    (x - 0.69)^2) + 0.5 * exp(-32000 * (x - 0.83)^2))
n = 256
t = 1:n/n
p = spike.f(t)*2-2

set.seed(111)
ntri=rpois(256,20)-9
result=simu_study(p,0.1,ntri)

par(mfrow=c(1,2))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: known variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashgen.out,col=4)
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: unknown variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashu.out,col=4)

mean(result$err$smashgen)
[1] 0.003198372
mean(result$err$smashgen.smashu)
[1] 0.003931562
ggplot(df2gg(result$err),aes(x=method,y=MSE))+geom_boxplot(aes(fill=method))+labs(x='')

\(\sigma=1\)

set.seed(111)
ntri=rpois(256,20)-9
result=simu_study(p,1,ntri)

par(mfrow=c(1,2))
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: known variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashgen.out,col=4)
plot(result$est$x/ntri,col='gray80',ylab='',main='smashgen: unknown variance')
lines(exp(p)/(1+exp(p)),col=1)
lines(result$est$smashu.out,col=4)

mean(result$err$smashgen)
[1] 0.01327303
mean(result$err$smashgen.smashu)
[1] 0.009787627
ggplot(df2gg(result$err),aes(x=method,y=MSE))+geom_boxplot(aes(fill=method))+labs(x='')

Session information

sessionInfo()
R version 3.4.0 (2017-04-21)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 16299)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252 
[2] LC_CTYPE=English_United States.1252   
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] ggplot2_2.2.1    smashrgen_0.1.0  wavethresh_4.6.8 MASS_7.3-47     
[5] caTools_1.17.1   ashr_2.2-7       smashr_1.1-5    

loaded via a namespace (and not attached):
 [1] Rcpp_0.12.16        plyr_1.8.4          compiler_3.4.0     
 [4] git2r_0.21.0        workflowr_1.0.1     R.methodsS3_1.7.1  
 [7] R.utils_2.6.0       bitops_1.0-6        iterators_1.0.8    
[10] tools_3.4.0         digest_0.6.13       tibble_1.3.3       
[13] evaluate_0.10       gtable_0.2.0        lattice_0.20-35    
[16] rlang_0.1.2         Matrix_1.2-9        foreach_1.4.3      
[19] yaml_2.1.19         parallel_3.4.0      stringr_1.3.0      
[22] knitr_1.20          REBayes_1.3         rprojroot_1.3-2    
[25] grid_3.4.0          data.table_1.10.4-3 rmarkdown_1.8      
[28] magrittr_1.5        whisker_0.3-2       backports_1.0.5    
[31] scales_0.4.1        codetools_0.2-15    htmltools_0.3.5    
[34] assertthat_0.2.0    colorspace_1.3-2    labeling_0.3       
[37] stringi_1.1.6       Rmosek_8.0.69       lazyeval_0.2.1     
[40] munsell_0.4.3       doParallel_1.0.11   pscl_1.4.9         
[43] truncnorm_1.0-7     SQUAREM_2017.10-1   R.oo_1.21.0        

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