Description Usage Arguments Details Value See Also Examples
Takes vectors of estimates (betahat) and their standard errors (sebetahat), and applies shrinkage to them, using Empirical Bayes methods, to compute shrunk estimates for beta. This is the more detailed version of ash for "research" use. Most users will be happy with the ash function, which provides the same usage, but documents only the main options for simplicity.
1 2 3 4 5 6 | bad_ash.workhorse(betahat, sebetahat, method = c("fdr", "shrink"),
mixcompdist = c("uniform", "halfuniform", "normal", "+uniform", "-uniform"),
optmethod = c("mixIP", "cxxMixSquarem", "mixEM", "mixVBEM"), df = NULL,
nullweight = 10, pointmass = TRUE, prior = c("nullbiased", "uniform",
"unit"), mixsd = NULL, gridmult = sqrt(2), outputlevel = 2, g = NULL,
fixg = FALSE, mode = 0, alpha = 0, control = list(), lik = NULL)
|
betahat |
a p vector of estimates |
sebetahat |
a p vector of corresponding standard errors |
method |
specifies how ash is to be run. Can be "shrinkage" (if main aim is shrinkage) or "fdr" (if main aim is to assess fdr or fsr) This is simply a convenient way to specify certain combinations of parameters: "shrinkage" sets pointmass=FALSE and prior="uniform"; "fdr" sets pointmass=TRUE and prior="nullbiased". |
mixcompdist |
distribution of components in mixture ( "uniform","halfuniform","normal" or "+uniform"), the default value is "uniform" use "halfuniform" to allow for assymetric g, and "+uniform"/"-uniform" to constrain g to be positive/negative. |
optmethod |
specifies the function implementing an optimization method. Default is "mixIP", an interior point method, if REBayes is installed; otherwise an EM algorithm is used. The interior point method is faster for large problems (n>2000), particularly when method="shrink". |
df |
appropriate degrees of freedom for (t) distribution of betahat/sebetahat, default is NULL(Gaussian) |
nullweight |
scalar, the weight put on the prior under
"nullbiased" specification, see |
pointmass |
logical, indicating whether to use a point mass at zero as one of components for a mixture distribution |
prior |
string, or numeric vector indicating Dirichlet prior on mixture proportions (defaults to "uniform", or (1,1...,1); also can be "nullbiased" (nullweight,1,...,1) to put more weight on first component), or "unit" (1/K,...,1/K) [for optmethod=mixVBEM version only] |
mixsd |
vector of sds for underlying mixture components |
gridmult |
the multiplier by which the default grid values for mixsd differ by one another. (Smaller values produce finer grids) |
outputlevel |
determines amount of output. There are several numeric options [0=just fitted g; 1=also PosteriorMean and PosteriorSD; 2= everything usually needed; 3=also include results of mixture fitting procedure (includes matrix of log-likelihoods used to fit mixture); 4= output additional things required by flash (flash_data)]. Otherwise the user can also specify the output they require in detail (see Examples) |
g |
the prior distribution for beta (usually estimated from the data; this is used primarily in simulated data to do computations with the "true" g) |
fixg |
if TRUE, don't estimate g but use the specified g - useful for computations under the "true" g in simulations |
mode |
either numeric (indicating mode of g) or string "estimate", to indicate mode should be estimated. |
alpha |
numeric value of alpha parameter in the model |
control |
A list of control parameters passed to optmethod |
lik |
contains details of the likelihood used; for general ash |
See readme for more details.
ash returns an object of class
"ash", a list with some or all of the following elements (determined by outputlevel)
fitted_g |
fitted mixture, either a normalmix or unimix |
loglik |
log P(D|mle(pi)) |
logLR |
log[P(D|mle(pi))/P(D|beta==0)] |
result |
A dataframe whose columns are |
A vector of posterior probability that beta is negative
A vector of posterior probability that beta is positive
A vector of estimated local false sign rate
A vector of estimated local false discovery rate
A vector of q values
A vector of s values
A vector consisting the posterior mean of beta from the mixture
A vector consisting the corresponding posterior standard deviation
call |
a call in which all of the specified arguments are specified by their full names |
data |
a list containing details of the data and models used (mostly for internal use) |
fit_details |
a list containing results of mixture optimization, and matrix of component log-likelihoods used in this optimization |
ash
for simplified specification of ash function
ashci
for computation of credible intervals
after getting the ash object return by ash()
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 | beta = c(rep(0,100),rnorm(100))
sebetahat = abs(rnorm(200,0,1))
betahat = rnorm(200,beta,sebetahat)
beta.ash = ash(betahat, sebetahat)
names(beta.ash)
head(beta.ash$result) #dataframe of results
head(get_lfsr(beta.ash)) #get lfsr
head(get_pm(beta.ash)) #get posterior mean
graphics::plot(betahat,get_pm(beta.ash),xlim=c(-4,4),ylim=c(-4,4))
CIMatrix=ashci(beta.ash,level=0.95) #note currently default is only compute CIs for lfsr<0.05
print(CIMatrix)
#Running ash with different error models
beta.ash1 = ash(betahat, sebetahat, lik = normal_lik())
beta.ash2 = ash(betahat, sebetahat, lik = t_lik(df=4))
e = rnorm(100)+log(rf(100,df1=10,df2=10)) # simulated data with log(F) error
e.ash = ash(e,1,lik=logF_lik(df1=10,df2=10))
# Specifying the output
beta.ash = ash(betahat, sebetahat, output = c("fitted_g","logLR","lfsr"))
#Illustrating the non-zero mode feature
betahat=betahat+5
beta.ash = ash(betahat, sebetahat)
graphics::plot(betahat,beta.ash$result$PosteriorMean)
betan.ash=ash(betahat, sebetahat,mode=5)
graphics::plot(betahat, betan.ash$result$PosteriorMean)
summary(betan.ash)
#Running ash with a pre-specified g, rather than estimating it
beta = c(rep(0,100),rnorm(100))
sebetahat = abs(rnorm(200,0,1))
betahat = rnorm(200,beta,sebetahat)
true_g = normalmix(c(0.5,0.5),c(0,0),c(0,1)) # define true g
## Passing this g into ash causes it to i) take the sd and the means
## for each component from this g, and ii) initialize pi to the value
## from this g.
beta.ash = ash(betahat, sebetahat,g=true_g,fixg=TRUE)
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