# Diversity prediction theorem

```ruby
func avg_error(m, v) {
    v.map { (_ - m)**2 }.sum / v.len
}
 
func diversity_calc(truth, pred) {
    var ae = avg_error(truth, pred)
    var cp = pred.sum/pred.len
    var ce = (cp - truth)**2
    var pd = avg_error(cp, pred)
    return [ae, ce, pd]
}
 
func diversity_format(stats) {
    gather {
        for t,v in (%w(average-error crowd-error diversity) ~Z stats) {
            take(("%13s" % t) + ':' + ('%7.3f' % v))
        }
    }
}
 
diversity_format(diversity_calc(49, [48, 47, 51])).each{.say}
diversity_format(diversity_calc(49, [48, 47, 51, 42])).each{.say}
```

#### Output:

```
average-error:  3.000
  crowd-error:  0.111
    diversity:  2.889
average-error: 14.500
  crowd-error:  4.000
    diversity: 10.500
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://trizen.gitbook.io/sidef-lang/programming_tasks/d/diversity_prediction_theorem.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.