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Our tables rating individual firms will be more valuable to you if you know how the data were gathered and how they should be interpreted.
We regularly survey area CHECKBOOK and Consumer Reports subscribers for their feedback on services they have used. For our survey on window installers, we asked consumers to rate their experiences with firms they had most recently used "inferior," "adequate," or "superior" on several aspects of service, including "doing service properly on the first try," "starting and completing service promptly," "letting you know cost early," "advice on service options and costs," and "overall performance." Our Ratings Tables show the percent of each firm's surveyed customers who rated it "superior" (as opposed to "inferior" or "adequate") on each question. Our Ratings Tables also show the percent of each firm's surveyed customers who rated it "superior" or "adequate" (as opposed to "inferior") for "overall performance."
We have included on our Ratings Tables all of the firms for which we received at least 10 ratings on our customer surveys. If a firm is not listed on our Ratings Tables, it simply means we did not receive at least 10 ratings for it.
Since many firms were rated by rather small numbers of raters, small differences between two firms in the percentage of raters who gave a particular rating (say, "superior") should be ignored. The table below gives a rough guide to minimum differences you should look for in deciding on one firm over another.
When using these survey data, remember that the questions are to some degree subjective and that the differences among firms might be explained by differences in the personalities, backgrounds, critical standards, and other characteristics of the raters or by biases these raters might have.
For firms that were evaluated in our last full, published report, our Ratings Tables show the number of complaints filed with government offices of consumer affairs in Fairfax, Howard, and Montgomery counties; the Office of the Attorney General for the District of Columbia; the Consumer Protection Division of the Maryland Attorney General's Office; and the Virginia Office of Consumer Affairs. These complaint counts are for a two-year period.
Our ratings tables also show counts of complaints filed with the Better Business Bureau of Metropolitan Washington, DC (BBB) for a three-year period.
When using the complaint information, keep in mind that complaints are not always justified; sometimes the customer is unreasonable. Remember that we didn't have a measure of business volume; large firms are more likely to incur complaints simply because they serve more customers. Also be aware that some firms may be at greater risk than others of incurring complaints because of the specific types of business they do.
We always recommend that you look for substantial differences in complaint counts. We also advise giving little weight to complaint counts if the total count against a firm is less than three or four.
Information reported on our Ratings Tables regarding areas served and services offered came directly from the firms' representatives. We called each firm to complete a survey over the phone and then followed up with a mailed verification form.
To compare prices, our shoppers made a number of calls to each of the firms included in our last full, published report and, without revealing their affiliation with CHECKBOOK, obtained prices for three different types of window installation jobs.
To compute our price index scores, we calculated an average price for each job for all the firms that quoted on that job. Next we compared each firm's price to the average. One firm might come in at 120 percent of the multi-firm average for a particular job, and another firm might come in at 90 percent. We took each firm's percentage score on each job, standardized it, and assigned a weight to each job, based on our judgment. We then averaged the standardized, weighted percentage scores to find how the firm compared to other firms overall. Finally, we multiplied this overall percentage score by a flat dollar amount, say, $100.
The price index score, then, is intended to indicate the relative prices we found for the firms, adjusted to the base of this flat dollar amount. These index scores are imperfect for various reasons: for instance, the jobs checked may not be representative; the weighting of various jobs in the index may not accurately reflect typical expenditure patterns; and the number of jobs is small.
All of the data must be interpreted in view of timeliness. Our customer survey data are from surveys conducted from January 2004 to April 2011. Survey respondents were asked to report on experiences in the preceding year. Our data on complaints for the BBB are for a three-year period dating back from a date in November or December 2009. Our data on complaints for the government offices of consumer affairs are for a two-year period between September 1, 2007 and August 31, 2009. The data from our survey of firms were collected from January to March 2010. Our price data were collected from July to December 2009.
For the most part, our tables include firms for which we collected 10 or more ratings on our customer survey during the customer survey period mentioned above, but we do not report data for periods prior to firms' changes of name and ownership. As a result, some large firms are not listed at all. If only name or ownership changed, we do report the data. Changes subsequent to the dates listed above may not be taken into account.
We give checkmarks to firms that score highest on a scoring system that we devise for each service field. Our scoring systems weight the various data in our tables and text based on our subjective judgment of their importance. Since the scores are based entirely on information presented, you can apply your own subjective judgments, and decide whether you prefer firms we have not given checkmarks. Where we do not have important data on a firm, we cannot give our checkmark.
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