Returns the improvement rate of your AB-test and answers if it's statistically significant
npm install ab-test-result    
Returns the improvement rate of your AB-test (``challengerImprovement`) and answers if it's statistically significant (`isSignificant`).
The result returned also contains a `statistics` property with calculated statistical values.
npm install --save ab-test-result
`javascript
var abTestResult = require('ab-test-result');
var test = {
controlVisits: 490, // required
controlConversions: 10, // required
challengerVisits: 500, // required
challengerConversions: 17 // required
};
var confidence = 0.9; // optional, defaults to 0.95
var result = abTestResult.calcResult(test, confidence);
/*
result = {
controlConversionRate: 0.02040816326530612,
challengerConversionRate: 0.034,
challengerImprovement: 0.666,
isSignificant: true,
statistics: {
controlStandardError: 0.006387435072946544,
challengerStandardError: 0.008104813384649889,
zScore: 1.317131652811523,
pValue: 0.09340000000000004
}
}
*/
``