function track_event(data) {
    // init instance of our function to do analytical tracking
    var analytics_mgr = new AnalyticsManager();

    // the event type we are tracking
    analytics_mgr.event_type = data.evt_type;
    analytics_mgr.event_data = data.evt_data;

    //do some GA tracking
    analytics_mgr.trackGA();
}

/**
 * main function to manage analytics tracking
 */
function AnalyticsManager() {
    // tells us what type of event we are tracking
    this.event_type = '';
    this.event_data = '';

    this.trackGA = function () {
        switch(this.event_type) {
            case 'modal_reg_show':
                try {
                    var pageTracker = _gat._getTracker("UA-6189017-1");
                    pageTracker._trackPageview('register/modal');
                } catch(err) {}
            break;
        }
    }
}