Updated 5/5: Late last week the Houston Chronicle reported that the Children at Risk findings used flawed statistical analysis.

"The mistake involved a 'growth index' as part of each school's ranking. The measure of how much individual students improved on state exams in reading and math from 2012 to 2013 was based on an inaccurate formula. Some results may have been off by decimal places while others had a bigger variation.

Original:

This week the nonprofit group Children at Risk released their annual school rankings, which look at the Texas Education Agency to rank 7,000 schools. By their own admission, Children at Risk's analysis has its flaws.

"The limitations posed by TEA data are valid criticisms for the school ranking system. Any erroneous data reported to or by TEA may have an effect on the rankings," the group said in a statement accompanying the rankings.

So what does that mean? Take it all with a grain of salt. Here are the 10 worst schools that all received an F letter grade, according to Children at Risk.

10.) George Cameron Scarborough High School

This northwest Houston architecture magnet school ranked 144. It made the dreaded "dropout factory" list seven years ago.

9.) Charles H. Milby High School

This East End high school ranked 146.

This southwest Houston school located in Brays Oaks ranked 147.

7.) James Madison High School

Madison, a science magnet school located in Hiram Clarke, is ranked 152. (This happened, recently. )

6.) Jack Yates High School

The Third Ward school ranked 148.

5.) Jesse H. Jones High School

This South Park school ranked 153. The HISD board voted last month to change Jones from a zoned school into an alternative career campus.

4.) Phillis Wheatley High School

The Fifth Ward school, also deemed a "dropout factory," has been on the chopping block in the past. It now shines with one of the nicest buildings in the district.

3.) Ross Shaw Sterling High School

This southeast Houston school is ranked 155. It's an aviation magnet that also made the "dropout factory" list in 2007.

2.) Kashmere High School

This school, located in the northern 610 Loop near Kashmere Gardens, was ranked 156. One of its claims to fame was that Jay-Z made a motivational stop here some ten years ago. On a more nefarious point, Kashmere was at the center of a dropout scandal a few years ago.

1.) Evan E. Worthing High School

This school in Sunnyside is at the bottom of the list at 157. Deemed a "dropout factory" in that 2007 study as well.