How We Gather (and How to Interpret) Our Data
Last updated December 2021
Our tables rating individual companies will be more valuable to you if you know how the data were gathered and how they should be interpreted.
Opinion Surveys
We surveyed area Checkbook and Consumer Reports subscribers for their feedback on services they have used. We also surveyed a random sampling of other area consumers. On our surveys, we ask consumers to rate their experiences with companies they had most recently used on several aspects of service. Our ratings tables show the percent of each company’s surveyed customers who provided a rating of “superior” (as opposed to “inferior” or “adequate”) for questions on our survey.
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 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 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
Our ratings tables report the number of complaints filed against individual 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 employees who do residential electrical 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 electrical 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.
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 2010 to November 2024. Survey respondents were asked to report on experiences in the preceding year. Our data on complaints for the Consumer Protection Division of the Washington Office of the Attorney General are for a two-year period between June 1, 2019 and May 31, 2021. The data from our survey of companies were collected from September to November 2021. Our price data were collected from July to October 2021.
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.
| A rough guide for deciding whether the difference between two percentages is important | If one firm had this number of ratings: | And a second had this number of ratings: | Do not give much importance to the difference between percentages unless the difference is at least this many percentage points: |
|---|---|---|---|
| Assuming the average of the two firms' percentages is 50 percent | 10 30 60 120 |
10 30 60 120 |
45 26 18 13 |
| Assuming the average of the two firms' percentages is 80 percent | 10 30 60 120 |
10 30 60 120 |
36 21 15 10 |