Google Analytics Experiments always chooses origin

Question

I'm setting up a multivariate test through Google Analytics. I created the experiment through the API, and everything is looking like its running, however, only the original is being selected and the variants aren't being served.

I've tried using incognito windows, and had a few other people visit the page as well, but everyone receives a page with ?utm_expid=XXXXXXXX-XX.YYYYYYYYYYYYYYYYYY.0 on the end, where the .0 seems to indicate "show original."

Any ideas why an experiment might always show the original? Here's my experiment as retrieved through the API.

{
    "id": "YYYYYYYYYYYYYYYYYYYYY",
    "kind": "analytics#experiment",
    "accountId": "AAAAAAAA",
    "webPropertyId": "UA-ZZZZZZZZZ-0",
    "profileId": "XXXXXXXX",
    "name": "Product Page - Grid Content",
    "description": "Test of product page grid content.",
    "created": "2013-11-22T15:53:32.634Z",
    "updated": "2013-11-22T16:27:15.406Z",
    "objectiveMetric": "ga:timeOnSite",
    "optimizationType": "MAXIMUM",
    "status": "RUNNING",
    "startTime": "2013-11-22T16:00:37.367Z",
    "rewriteVariationUrlsAsOriginal": true,
    "winnerConfidenceLevel": 0.95,
    "minimumExperimentLengthInDays": 7,
    "trafficCoverage": 1,
    "equalWeighting": true,
    "variations": [{
        "name": "Newest Products (Original)",
        "url": "http://mystore.com/product/pastel-lipstick",
        "status": "ACTIVE",
        "weight": 0
    }, {
        "name": "Most Popular Products",
        "url": "?",
        "status": "ACTIVE",
        "weight": 0
    }, {
        "name": "Related Products",
        "url": "?",
        "status": "ACTIVE",
        "weight": 0
    }],
    "servingFramework": "REDIRECT",
    "editableInGaUi": true
}

UPDATE:

I've suspected this might have something to do with those weight: 0 fields under variations[]. I'm not entirely sure why they appear as weight: 0, or whether that actually prevents variations from showing.

Originally, I wanted to set url: "?" for my variations because I wanted to avoid polluting my query string. Instead of using different URLs/query string variables to determine which variation to show, I used the utm_expid query string variable the GA Experiment redirect adds to determine which variation to show. Although the API accepted these URLs without issue, I'm not sure they're actually considered 'valid.' So I tried changing the URLs to be ?mvt=1 and ?mvt=2 respectively, and saw the weights changed to 0.3333 and variations serve.

Although changing the URL seems to work, does anyone have a thorough explanation for what or why this is happening?

Answer 1

There is an open issue on this https://code.google.com/p/analytics-issues/issues/detail?id=377. If you subscribe to that then you'll get notified when it's fixed.