function main() {

    /**
     * Google Drive spreadsheet url
     *
     * @type {string}
     */
    var spreadsheetUrl = "[URL spreadsheet]";

    /**
     * Supported values:
     * TODAY, YESTERDAY, LAST_7_DAYS, THIS_WEEK_SUN_TODAY,
     * LAST_WEEK, LAST_14_DAYS, LAST_30_DAYS, LAST_BUSINESS_WEEK,
     * LAST_WEEK_SUN_SAT, THIS_MONTH, LAST_MONTH, ALL_TIME
     *
     * @type {string}
     */
    var dateRange = 'LAST_30_DAYS';

    /**
     *
     * @type {Sheet}
     */
    var qualityScoreSheet = SpreadsheetApp.openByUrl(spreadsheetUrl).getActiveSheet();

    /**
     *
     * @type {Date}
     */
    var date = new Date();

    /**
     *
     * @type {AdWordsApp.CampaignSelector}
     */
    var campaigns = AdWordsApp.campaigns()
        .withCondition("Status='ENABLED'")
        .get();

    while (campaigns.hasNext()) {

        /**
         *
         * @type {AdWordsApp.Campaign}
         */
        var campaign = campaigns.next();

        /**
         *
         * @type {number}
         */
        var campaignImpressions = 0;

        /**
         *
         * @type {number}
         */
        var qualityScore = 0;

        /**
         *
         * @type {AdWordsApp.KeywordSelector}
         */
        var keywords = campaign.keywords()
            .withCondition("AdGroupStatus = 'ENABLED'")
            .withCondition("Status = 'ENABLED'")
            .forDateRange(dateRange)
            .get();

        while (keywords.hasNext()) {

            /**
             *
             * @type {AdWordsApp.Keyword}
             */
            var keyword = keywords.next();

            /**
             *
             * @type {AdWordsApp.Stats}
             */
            var stats = keyword.getStatsFor(dateRange);

            /**
             * Add quality score * impressions to total campaign quality score
             */
            qualityScore = qualityScore + keyword.getQualityScore() * stats.getImpressions();

            /**
             * Sum all impressions for this campaign
             */
            campaignImpressions = campaignImpressions + stats.getImpressions();
        }

        /**
         * Calculate the average quality score
         *
         * @type {number}
         */
        var qualityscoreForCampaign = qualityScore / campaignImpressions;


        /**
         * Add a new row to the spreadsheet with the quality scode
         */
        qualityScoreSheet.appendRow([date, qualityscoreForCampaign, campaign.getName()]);


    }
}