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GreatSchools Ratings FAQ
Read these Frequently Asked Questions to learn more about how GreatSchools Ratings are calculated and what they can tell you about a school.

GreatSchools Ratings Overview What do GreatSchools Ratings tell me? Our ratings provide an overview of a school's test performance by comparing the school's state standardized test results to those of other schools in the state. Ratings are given for each grade and student category (gender, ethnicity or other student group) for which test results are available. Keep in mind that when comparing schools using GreatSchools Ratings, it's important to factor in other information, including the quality of each school's teachers, the school culture, special programs, etc.
Which tests are GreatSchools Ratings based on? GreatSchools Ratings are based on each state's main standardized tests. To get the details on specific tests used in your state, go to any school's ratings page and click on the link below the ratings that says "See which tests were used."
Why don't private schools have GreatSchools Ratings? Private schools are not required to publicly report test results, so they do not have GreatSchools Ratings.
Why do some public schools not have GreatSchools Ratings? If a public school does not have GreatSchools Ratings, there were no test scores reported for that school, results were incomplete or there were not enough results available across all schools in the state to make a valid comparison.
Can I compare GreatSchools Ratings across different states? No, GreatSchools Ratings cannot be compared across states, because they are based on test results and different states use different tests.

GreatSchools Ratings Calculation What data is used in calculating GreatSchools Ratings? GreatSchools Ratings are based on the most recent available standardized test results for schools in each state. The results we use are typically the percentage of students scoring at or above the proficient level on the test in each grade and subject (e.g., grade 4/math) and each grade, subject and student category (e.g., grade 4/math/Hispanic students). The proficiency levels and student categories are defined by the state Department of Education.
How are the By Grade ratings calculated? We start by calculating ratings for each grade/subject combination; then we average those ratings into the By Grade ratings you see on the page.
The test results (as defined above) for all schools for a given grade/subject are sorted from low to high and divided into deciles, or 10% portions. The bottom 10% of schools get a rating of 1, the next 10% get a 2, on up to 10, which indicates the school's result is in the top 10%. If there are several identical values that overlap from one rating decile to another, they are given the higher rating.
Once ratings are established for all grade/subject combinations, each school's ratings are averaged to create the By Grade ratings that you see on the page. For example, the rating shown for grade 4 is an average of that school's ratings for each subject tested in grade 4. If the grade 4 rating is a 10, it means that, on average, fourth-grade students at the school performed better than 90% of the fourth-grade students whose test results were reported at schools statewide.
To ensure that the ratings are not based on a set of data that is too small to be statistically reliable, a rating is not calculated if fewer than 50 schools reported test results for a particular grade/subject combination.
How are the By Category ratings calculated? The By Category calculation is similar to the By Grade calculation. We start by calculating ratings for each grade/subject/category combination; then we average those ratings into the By Category ratings you see on the page.
The ratings for each student category provide an alternate view of a school's performance, comparing the performance of a given group of students at the school with the overall student population of the state. The categories are defined by the state. For example, the California Dept. of Education releases separate test results (called disaggregated results) for 26 student categories, including gender, ethnicity and special student groups (e.g., students with disabilities).
To create the ratings for each category, we compare the performance of that category in each grade/subject to the decile rankings we have established for that grade/subject. The performance value used is the percentage of students in the category scoring at or above the proficient level, as defined by the state.
You can use the By Category ratings to compare student groups at the school. For example, if one category receives a rating of 3 and another category receives a rating of 7, this suggests that an achievement gap exists between these categories of students at this school.
How are the Overall Ratings calculated? The Overall Rating for each school is calculated by averaging that school's ratings for all grade/subject combinations. For example, if a state test is given in reading and math in grades 3 through 10, the Overall Rating for a school serving grades K-5 would be the average of the ratings for grade 3/math, grade 3/reading, grade 4/math, grade 4/reading, grade 5/math and grade 5/reading.
Note that the Overall Rating is not an average of the By Grade ratings you see displayed on the page, but rather, an average of the underlying grade/subject ratings, which are used to create both the By Grade ratings and the Overall Rating. We use these underlying ratings, instead of averaging the By Grade ratings, to reduce rounding errors.
Why are some student groups not shown? The different student groups shown in the By Category section are defined by the state Department of Education. To protect students' privacy, if there are fewer than 10 students in a group, that group's test score is not publicly reported. If no test results are available for a particular student group, no rating can be created for that group.
How can a school's Overall Rating be high if the ratings for certain student groups are low, or vice versa? If a school's Overall Rating is high, that means its test scores are better than the test scores of most other schools in the state. If a particular student group's rating is low, that means the test scores for that particular group are lower than the scores of most other students in the state. This may mean the school is helping most students achieve at a high level, but is not serving particular groups of students as well.
Conversely, if a school's Overall Rating is low, that means its test scores are lower than the test scores of most other schools in the state. If a particular student group's rating is high, that means the test scores for that particular group are better than the scores for most other students in the state. This may mean the school is helping certain groups of students achieve at a high level, but is not serving the majority of students as well.
How are the District and City Ratings calculated? District Ratings are calculated by taking the Overall Rating for each school in the district and weighting it by the number of students enrolled at the school. We then take the average of the weighted ratings. Similarly, City Ratings are calculated by averaging the weighted Overall Rating for each school in the city.
GreatSchools Ratings are based on each state's main standardized tests. To get the details on specific tests used in your state, go to any school's ratings page and click on the link below the ratings that says "See which tests were used."
What is "weighting" and why is it used in District and City Ratings calculations? Weighting each school's Overall Ratings means that schools with more students count more than schools with fewer students. Weighting makes the District and City Ratings more representative of the performance of the entire student population.
Why do some districts and cities not have GreatSchools Ratings? District and City ratings are not created if there are too few schools with ratings in the district or city. For districts and cities with fewer than 10 schools, at least 50% of the schools must have ratings in order for the district or city rating to be calculated. For districts and cities with 10 or more schools, at least 30% of the schools must have ratings.

GreatSchools Ratings VS. Other Ratings How do GreatSchools Ratings compare to the ratings given by the state Department of Education? Some states have their own ratings systems, and their method of calculating ratings may differ significantly from the way GreatSchools Ratings are calculated. GreatSchools Ratings are based solely on test performance for one year. Check with your state Department of Education to find out if your state has a rating system and how its ratings are calculated.
Updated April 2008

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Comments From GreatSchools.net Users
11/17/2009:
"I guess rating system might be little unfair but test score will tend to remain important benchmark...as our society judges' us based on test scores (i am not saying it is a right approach). I think it would be helpful/insightful if greatschool.net can provide secondary ranking based on other factors."
11/2/2009:
"My child goes to a school that has a rating of ten. While I work in numerous schools in the next city over that have ratings as low as one and two. I think this rating on test scores only is absolutely ridiculous. Some of the things that are being taught in these lower rated schools is actually more in depth and challenging that the higher rated schools. Sadly, I would say that the only reason that some schools have a higher rating is not based on the professionalism and level of expertise of the teacher, but of the education and time available of the parents. This rating system really degrades schools in districts with lower socio-economic status!! "
10/6/2009:
"Test scores are really only one means to measure a school, but unfortunately, it's given a lot of weight--especially from parents looking to place their child in a 'good school.' My son went to one of the top rated schools (based on test scores) for 6th grade but he was miserable. He had 2 hours of homework a night because the teachers had to whiz through the book in order to 'get it all in' before the testing in the spring. What did he actually retain? He came away hating school. Now he attends a project based learning school. He is learning to develop a sense of curiousity, and how to find the answers to his questions. He now has a love of learning. That is a far better measure of how he is doing as far as I'm concerned-- give a man a fish (teach to the test) and he'll eat one good meal (do well on the test); give him a fishing rod (love of learning) and he'll feed himself for life (continue to learn). "
08/24/2009:
"I think that rating a school based solely on test scores is unfair. I think that other factors should be included. I know that it is likely the easiest way to have a data driven rating, but I can tell you that I completely disagree with my school's 'rating'. As a teaching professional in that school AND as a parent, I can assure you we are NOT A 7."
06/24/2009:
"Your test scores are not accurate for our local school, I don't know about others. I have tried to correct this with with no luck. I think it is sad because lots of parents will look at these numbers and judge the school and its abilities and it is giving an unfair view. If you want the TRUE results of your school, look it up under your districts webpage. They generally have them listed and they are CURRENT."
05/28/2009:
"This year our elementary school's scores all improved, but the rating went from a 10 to a 9. Maybe our improvements did not keep up with statewide improvements, or perhaps there were changes to state test scoring methods. It seems odd that even improvement can lead to a downgrade, and it makes me question the effectiveness of a ten-point scale. Given the ambiguity inherent in the system, maybe quintiles would be more honest than deciles. Also, in response to 02/18/2009 and 04/09/2009 below, I'm glad that the scores are *not* weighted by socioeconomic factors; that would only cover up and perpetuate the terrible injustice of a system in which low-income neighborhoods are *still* consistently short-changed. Improvement from a 2 to a 4 at an urban school is highly commendable, and improvement/decline should be noted visibly; but it would still be misleading to say that the students are scoring at, say, a 'weighted 8' when they're actually scoring at a 4 as compared to the state! wide average."
05/27/2009:
"What a joke your ratings are. The Downtown school is nationally recognized as one of the top ten elemenatary schools in the country. It was even featured in a book based on the Disney way for innovation in education...and you rate it a 4. What a diservice you do to not only the Downtown school, but your obviously shallow approach to determining what a 'Great School' is. You should be ashamed of yourself. "
05/13/2009:
"Hello, I love your website. Can you tell me where I can find a comparison of this rating system with NYS report card on schools?"
05/5/2009:
"awesome thanks!!! =D"
04/9/2009:
"I would echo the concerns of the person giving feedback on 2-18-09 (see next paragraph) especially at the early elementary level. Can this site provide any insight as to why other parameters aren't included in their rating? Is it simply that it would cost too much to provide a more in-depth evaluation? 'So my limited understanding of trying to measure schools' performance is that THE BIG issue is controlling for poverty/socialeconomic status. Schools in wealthy areas will tend to have high test scores. Schools in high-poverty areas will tend to have lower test scores. If you are trying to directly measure how effective a school is, you somehow need to control for these factors. Schools with good (but not great) scores in wealthy areas might actually be doing a poor job. Schools with middling (but not horrible) scores in very troubled areas might actually be doing a great job. Yet as I read your description of your rating system, it doesn't look like you have ANY method for addressing this issue. Can you confirm whether or not I'm missing something, and whether you do control for these factors? Thanks.'"
02/18/2009:
"So my limited understanding of trying to measure schools' performance is that THE BIG issue is controlling for poverty/socialeconomic status. Schools in wealthy areas will tend to have high test scores. Schools in high-poverty areas will tend to have lower test scores. If you are trying to directly measure how effective a school is, you somehow need to control for these factors. Schools with good (but not great) scores in wealthy areas might actually be doing a poor job. Schools with middling (but not horrible) scores in very troubled areas might actually be doing a great job. Yet as I read your description of your rating system, it doesn't look like you have ANY method for addressing this issue. Can you confirm whether or not I'm missing something, and whether you do control for these factors? Thanks."
02/5/2009:
"This site is an ANSWER to my PRAYERS!! Trying to figure out the differences between schools has been confusing, to say the least. Kind of like trying to buy the best mattress....very confusing because there is no way to compare apples to apples. And the information about schools is all over the place. I found this site by accident, and have sent the link to all my friends. I have spent hours on here, absorbing all the excellent information available at the click of my mouse! THANK YOU!"
01/21/2009:
"I base my pick on a school to what great schools give me about test scores. Is it wise to do that? I think so I want my kids in a good school. In texas it is all about the taks test. What should i really pick a school based on. What if you don't have internet how a can parents pick a school if they are moving to a new area?"
01/15/2009:
"On 10/2/08 a writer wrote: 'How many adults have used algebra, geometry, trigonometry, or calculus in the last year?' 'As long as subjects are irrelevant, students will continue to get low test scores.' The answer is 'Every adult.' Investing wisely and getting the best rate on a mortage require algebra. All of these math skills are frequently utilized, although less frequently do adults sit down and work math problems out of a math book. The only people who refer to mathematics as 'irrelevant' are themselves irrelevant except in discussions of ignorance. The inability to recognize that these math skills are necessary on a daily basis is the fundamental problem with math education."
01/9/2009:
"Please keep on writing your comments about the school your child is going. It has been a great help!"
11/5/2008:
"Hi. I would like to know how my school is comparing nationwide. In the past you had 2 #s for example a school could be a 10 but a 5 nationwide. Where do I find this information. "
11/5/2008:
"I like the schools they are very competitive and very socialized."
10/13/2008:
"Although there may be some validity to this rating service, it certainly has a limited use based on the results I have reviewed. Additionally, a score on a standardized achievemnt test does not always reflect an accurate picture of a student's level of achievement nor the quality of instruction; research indicates multiple assessments should be given to provide a more comprehensive picture of achievment for a student. Additionally, I am concerned about a parent(s) who has/have an axe to grind with a teacher and take it out on the school in this type of forum. Let's be honest. There are a number of parents in each community who are operating under a high level of dysfunction. "
10/2/2008:
"Students will never get the education they need in any school--no matter what its ratings are--unless the curriculum is revised to meet their needs. For example, how many adults have used algebra, geometry, trigonometry, or calculus in the last year? Why have these subjects in high school unless the students are going to become mathematicians or engineers? It would be better to teach sound fiscal management, how to balance a checkbook, how to invest wisely, and how to get the best rates on loans and mortgages. As long as subjects are irrelevant, students will continue to get low test scores."
10/2/2008:
"I agree with some of the other feedback comments. How come many of the people leaving feedback can't spell or construct a sentence. No wonder our children are having problems. I had to read some of the feedback a few times to try and figure out what the point was or what the sentence really was saying. I had to fill in words and reconstruct sentences as I read. Is this do to being lazy?"
10/2/2008:
"We need schools that can measure up to the very best national standards. We need math/science, literature/ language arts, music ....not just playing a c.d. and singing The Alphabet Song) We need art... (not just coloring) We need a theatre/stage, where children are encouraged to speak, debate, sing, dance, etc. Without a voice, one has no power. For too long, Mississippi has been a people without much education/power. It needs to start in the lower grades...kindergarden. We need health/physical education...both structured and unstructrured play. Kids need time to eat...NOT starting at 10:30 .....maybe a break and snack then, but not lunch. They do need recess where GOOD foods are offered......fruits, low fat cheeses, non-fat milk. We need lunches with veggie salads...not iceberg lettuce with no nutrition, but Romaine lettece. We need to leave off the hot dogs, pizza unless the buns/crusts are whole wheat and the hotdogs/pepperoni have no nitrates, coloring, high sodium,m.s.g., human growth hormones. We need milk without human growth hormones and so much fat. Doctors often tell us now to start kids on non-fat milk after age two. "
09/25/2008:
"I would not go to a school based on its ratings because statistically speaking they are just that randomly put there so you will think the school your children are attending is a great school. My daughter goes to the hornell high school and she has a learning disability. Which I have found out a couple of years ago it is dyslexia. Now how can you help a child with this kind of learning disability if you don't know what it is your self? How can you give a child a title learning disabled and not know what the disability is so she or he can be helped better in a school setting? IEP's are great but if you don't follow them and they are only there because the state requires them then your focus for these children are off balance if you ask me. The no child left behind act was developed I believe to get these kids with disablities so they can have a regular diploma instead of the ones the school gives to them now days which don't amount to a hill of beans. It was also developed s! o the drop out rate for low income children and others will be dropped and those kids will be helped more. Your focus is off if you are only doing for those who you want to do for. It is not a good sign for the system."
09/18/2008:
"The only problem I'm still facing w/ my son school , and is since last year(still nobody do anything) is about the police man driving a golf car on side walk through students, parents and another relative like small siblings during the dismissal time.Last year for few second we do not face and accident because his incorrect way of drive on the side walk but nobody is listening ."
09/15/2008:
"So is it ok to choose a school based on the current ratings? Are the Ratings accurate? Is a school really a good school because of it's ratings? Is it possible they are fixed? I would hate to send my kid to school because it had a good rating and later find out the school is crap."
08/22/2008:
"I am totally outraged that , as a Afro-American director of an afterschool activities youth center serving children, with a special concern for children from disadvantaged circumstances, our organization cannot know how these children are academically progressing. Since many of these children are 'bi-racial' offsprings of single black females, how do the schools report their Tests; white if they do well/'na' and lump them with the Afro-American kids whose scores are usually low. When I ask the school district how the Afro-American kids scores ranked, I am told that there aren't enough black kids in the classroom taking the test (10 are more) so the (na) notation is all the info that concerned citizens can see on reports to the state educ. of educ. Am I the only retired teacher that believes this kind of reporting is questionable and absolutely not helpful for mature adults mentoring and tutoring disadvantaged kids? This possibly leads to the failing of so many minority kids in rural schools because if their reported scores are 'na' it would takes very caring and determined teachers of these kids for these kids show academic progress. Otherwise, I understand why so many end up in time-out rooms, suspended, or expelled. The federal Dept. of Educ. needs to make a study of the 'na' reports for minority kids living in small, rural towns in America."
07/7/2008:
"I am moving to Michigan, Farmington Hills area, and would like to choose a house based on the best schools. I am a foreigner, so I am not familiar with the way children are assigned to schools. Can I choose a school pertaining to a certain school district (provided we are living there), or is it 'assigned' to my child by the district/state/whatever??? Does my child, who has been in International (british system) School for the last 5 years (he's 10), need to test? Will the school 'assignment' be based on his test scores???"
06/30/2008:
"I am confused and very surprised that the overall rating for CV is a 6 and the test scores and the overall performance of the students is superior in comparison of the community. Test scores were five points lower than last year, but the scores are so high I don't see a correlation. I don't agree with the rating of 6 in comparison to the performance of the children. "
04/25/2008:
"To the 4/22 grammar critique posting. People who live in glass houses should not through stones. I suggest you read up on correlative conjunctions. It is sad that these parents can neither spell nor construct a sentence. or It is sad that these parents cannot spell or construct a sentence. "
04/24/2008:
"Everyone's comments are great, but it is sad that even these parents cannot spell nor construct a sentence. How can you teach your child if your own grammar and spelling is atrocious?"
04/16/2008:
"My child is currently a fourth grade student at an A listed school. I have heard nothing out of this school except we need to get good scores on the FCAT;that seems to be the only focus, not that my child doesn't seem to understand the essays he has to write or that he really doesn't know how to spell a word correctly. I have been to the school and they seem to think that he will be just fine...I argued that he would need spelling and comprehension in the future and when the children are young the standards are set for their future. I left that day and took my child's education into my hands, we practice spelling and writing nightly and I told him not to feel pressured by some ridiculous test that really isn't going to get him anywhere in the future. My concern is how many children do not get the help they need. I do not believe placing so much pressure on these children for a test that really only accomplishes one thing....more money for the school..to do what with, is th! e question all parents should be asking, because I don't think it's going to the education of our children!!!!!"
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