Hi guys, I am very new to Stan. I currently have a model here. I am wondering how could I adjust to use ADVI? Would ADVI be faster than MCMC? Thank you for your help! Any advice would be awesome!

functions {

real betaModeConc_lpdf(real parm,real m,real c) {

return beta_lpdf(parm|m*(c-2)+1, (1-m)*(c-2)+1);

}

}data {

int<lower=0> N_DNA;

int<lower=0> a[N_DNA];

int<lower=0> b[N_DNA];

int<lower=0> N_RNA;

int<lower=0> k[N_RNA];

int<lower=0> m[N_RNA];

}parameters {

real<lower=0,upper=1> p;

real<lower=0,upper=1> qi[N_RNA];

real<lower=0> theta;

real<lower=2> c;

real<lower=0> s;

}transformed parameters {

real<lower=0,upper=1> q;

q=thetap/(1.0-p+thetap);

}model {

// Parameters:

c ~ gamma(1.1, 0.0005);

s ~ gamma(1.1,3);

log(theta)/s ~ normal(0,1);

target+=-log(theta)-log(s);

for(i in 1:N_RNA)

qi[i] ~ betaModeConc(q,c);// Likelihoods:

for(i in 1:N_DNA)

a[i] ~ binomial(a[i]+b[i],p);

for(i in 1:N_RNA)

k[i] ~ binomial(k[i]+m[i],qi[i]);

}