How to reparameterize this model, geting low E-BFMI error

Modeling
1

This is the stan code, its for modeling a cricket simulation as described in this paper:
Modelling and simulation for one-day cricket

functions {

real D(int number,real delta_1,real delta_2){

if(number>0 && number <= 3 )

  return 0.0;



else if(number >3 && number <=6)

  return delta_1;

else if(number >6)

  return delta_1 + delta_2;

else return 0;

}

vector mean_mat(matrix X){

vector[7] means;

for(i in 1:7){

means[i] = mean(X[i,]);

}

return means;

}

}

data {

int<lower=1> N; 

int<lower =1> BatNum;

int<lower =1> BowlNum;

int BatIndex[N];

int BowlIndex[N];

int<lower=1,upper=9> l[N];

int<lower=1,upper=7> F[N];

int<lower=1> index[N];

int matchballs;

}

parameters {

ordered[7] alk[9];

real<lower=0> sigma;

real<lower=0> tau;

real mu_1[BatNum];

real mu_2[BowlNum];

real<lower=0,upper=1> delta_1;

real<lower=0,upper=1> delta_2;

}

transformed parameters{

real delta[9];

for(n in 1:9){

delta[n] = D(l[n],delta_1,delta_2);

}

}

model {

//

matrix[N,7] s;

delta_1 ~uniform(0,1);

delta_2 ~uniform(0,1);

  

sigma ~ gamma(1,1);

tau ~ gamma(1,1);

mu_1 ~ normal(0,sqrt(1/tau));

mu_2 ~ normal(0,sqrt(1/tau));

//delta_1 = uniform_rng(0,1);

//delta_2 = uniform_rng(0,1);



for(t in 1:9){

  alk[t] ~ normal(0,sqrt(1/sigma));

}

for(i in 1:N){

for(t in 1:7){

s[i,t] = alk[l[i],t] - mu_1[BatIndex[i]] - delta[l[i]] + mu_2[BowlIndex[i]];

}

}

F~ categorical_logit(mean_mat(s’));

}

please ask any questions you may have or if you need more information

2

Based on this:

mu_1 ~ normal(0,sqrt(1/tau));
mu_2 ~ normal(0,sqrt(1/tau));

I think your best bet is to start with some non-centerings. Check this for the how and why.

Also you can surround your code on both sides by three backticks (put ``` before and then another three after) and Discourse does a pre-formatted code block that makes it much easier to read (there’s also a button in the toolbar to the right of the quote button and to the left of upload).

1 Like
3

Thank you, tried running again with your non-centering approach. Also Im new here cant seem to find the edit button to put ‘’’ quotation marks

4

Actually I lied – the code button does indents not ticks to get preformated code, but it works either way.

Here’s a screenshot:

image

And this is what it renders to:

code goes here

Those are just three backticks (you can copy paste them from here ```).

5

You can also use tildes

~~~
code goes here
~~~

So when teaching someone to use code formatting you can write

~~~
```stan
stan code goes here
```
~~~

and it shows up as

```stan
stan code goes here
```

no need for screenshots.

2 Likes