a postman script to calculate the response time average and standard deviation of a request

postman-response-time-metrics.js

function standardDeviation(values, avg) {
    var squareDiffs = values.map(value => Math.pow(value - avg, 2));
    return Math.sqrt(average(squareDiffs));
}

function average(data) {
    return data.reduce((sum, value)=>sum + value) / data.length;
}

if (responseCode.code === 200 || responseCode.code === 201) {
    response_array = globals['response_times'] ? JSON.parse(globals['response_times']) : []
    response_array.push(responseTime)
    postman.setGlobalVariable("response_times", JSON.stringify(response_array))

    response_average = average(response_array);
    postman.setGlobalVariable('response_average', response_average)

    response_std = standardDeviation(response_array, response_average)
    postman.setGlobalVariable('response_std', response_std)
}

Because of some deprecated code parts here is the code for the main part of the script for current Postman version (7.36.1):

if (pm.response.code === 200 || pm.response.code === 201) {
    response_array = pm.globals.get('response_times') ? JSON.parse(pm.globals('response_times')) : []
    response_array.push(pm.response.responseTime)
    pm.globals.set("response_times", JSON.stringify(response_array))

    response_average = average(response_array);
    pm.globals.set('response_average', response_average)

    response_std = standardDeviation(response_array, response_average)
    pm.globals.set('response_std', response_std)
}

When you want to use collection variables, use pm.collectionVariables instead of pm.globals. For environment variables use pm.environment.