Probability density

Today I am continuing to look into statistics to see if this is something that I want to learn more about by writing a post on Probability density.

Sometimes it is better to test for a range, then an precise value.

Probability density has to do with the issue of testing for a certain value that may not ever really happen, so it is better to test for a range. That is the probability of it happening is very close to zero, or is pretty much zero, but not if we are talking about a small range rather than a very precise value.

A javaScript example of probability density

For an example of probability density I made a quick module that creates a bunch of objects that have a number that represents the amount of time that passed when a bug died.

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var bugs = (function() {
var api = {};
// initilize
api.init = function(options) {
options = options || {};
this.count = options.count || 100;
this.tBase = options.tBase || 1000;
this.tRange = options.tRange || 2000;
this.bugs = [];
this.st = new Date();
var i = 0;
while (i < this.count) {
this.bugs.push({
dieAt: Math.random() * this.tRange + this.tBase
});
i += 1;
}
};
// get a count of how many died at a given time stamp, and range
api.diedAtCount = function(time,range){
// dfault time at the base + 1/2 range
time = time || Math.floor(this.tBase + this.tRange / 2);
// default range to 10ms
range = range === undefined ? 10 : range;
return this.bugs.reduce(function(acc,bug){
if(bug.dieAt >= time-range && bug.dieAt <= time + range){
return acc += 1;
}
return acc;
},0);
};
api.diedAtPer = function(time,range){
// dfault time at the base + 1/2 range
time = time || Math.floor(this.tBase + this.tRange / 2);
// default range to 10ms
range = range === undefined ? 10 : range;
var died = this.diedAtCount(time,range);
return died / this.count;
};
api.init();
return api;
}());

Conclusion

I will be holding off on expanding my collection of posts on statistics until I work out more demos, and refine my understating of things.