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How We Gather (and How to Interpret) Our Data

Opinion Surveys

We regularly survey area CHECKBOOK and Consumer Reports subscribers for their feedback on services they have used. For our survey on window washing services, we asked consumers to rate their experiences with companies they had most recently used "inferior," "adequate," or "superior" on several aspects of service, including "doing work properly on the first try," "starting and completing work promptly," "letting you know cost early," "neatness of work," and "overall performance." Our Ratings Tables show the percent of each company's surveyed customers who rated it "superior" (as opposed to "inferior" or "adequate") on each question.

We have included on our Ratings Tables all of the companies for which we received at least 10 ratings on our customer surveys. If a company is not listed on our Ratings Tables, it simply means we did not receive at least 10 ratings for it.

Since many companies were rated by rather small numbers of raters, small differences between two companies 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 company over another.

When using these survey data, remember that the questions are to some degree subjective and that the differences among companies might be explained by differences in the personalities, backgrounds, critical standards, and other characteristics of the raters or by biases these raters might have.

Complaint Counts and Rates

For companies that were evaluated in our last full, published report, our Ratings Tables report the number of complaints filed against individual companies with the Better Business Bureau (BBB) for a three-year period, and the number of complaints filed against companies with the Consumer Protection Division of the Illinois Office of the Attorney General for a two-year period.

Where we were able to, we have also reported on our Ratings Tables a complaint rate for each company, calculated by dividing the number of complaints by our measure of the number of full-time-equivalent workers who do residential window cleaning work for the companies. These complaint rates are intended as a rough way to take into account volume of work and the fact that companies that do more work are exposed to a greater risk of incurring complaints.

When using the complaint information, keep in mind that complaints are not always justified; sometimes the customer is unreasonable. Also, be aware that some companies may be at greater risk than others of incurring complaints because of the specific types of business they do. And remember that the measure of business volume we use in calculating complaint rates (the number of full-time-equivalent workers who perform residential window cleaning work) is at best a very rough indicator.

We always recommend that you look for substantial differences in complaint counts and rates. We also advise giving little weight to complaint counts if the total count against a company is less than three or four.

Price Index Scores

To compute our price index scores, we calculated an average price for each job or item for all the companies that quoted on that job or item. Next we compared each company's price to the average. One company might come in at 120 percent of the multi-company average for a particular job, and another company might come in at 90 percent. We took each company's percentage score on each job or item, standardized it, and assigned a weight to each job or item, based on our judgment. We then averaged the standardized, weighted percentage scores to find how the company compared to other companies 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 companies, adjusted to the base of this flat dollar amount. These index scores are imperfect for various reasons: for instance, the jobs or items checked may not be representative; the weighting of various jobs or items in the index may not accurately reflect typical expenditure patterns; and the number of jobs or items is small.

Areas Served

Information reported on our Ratings Tables regarding areas served came directly from the companies' representatives. We mailed each company a survey. For companies that did not respond to our mailed survey, our researchers called each company to complete a survey over the phone and then followed up with a mailed verification form.

Timeliness of the Data

All of the data must be interpreted in view of timeliness. Our customer survey data are from surveys conducted from January 2004 to December 2013. 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 between December 1, 2011 and January 31, 2012. Our data on complaints for the Attorney General's office are for a two-year period between September 1, 2009 and August 31, 2011. The data from our survey of companies were collected from December 2011 to January 2012. Our price data were collected from August to December 2011.

For the most part, our tables include companies 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 companies' changes of name and ownership. As a result, some large companies 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.

Top Ratings

We give checkmarks to companies 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 companies we have not given checkmarks. Where we do not have important data on a company, we cannot give our checkmark.


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