Question: What is the ranking system used in combat sports, including boxing and mixed martial arts, of who the better fighters are relative to their weight, by which measure the Polish mixed martial artist Joanna Jędrzejczyk is rated the number 1 female MMA fighter in the world?
Context: Katja Kankaanpää (] , born June 30, 1981) is a Finnish former mixed martial artist who competed in the strawweight division.  She is currently signed with Invicta FC.  Kankaanpää started martial arts training at her teens when she was 15 years old with Goju-ryu karate.  Later she had interest about combat sports by training submission wrestling and other combat arts.  Katja leads the Nordic (all Skandinavia) strawweight rankings and Finnish women, all weight classes MMA rankings.  On January 2, 2015 she was awarded 'Nordic Female Fighter of the Year'.  The same month, Finnish sports journalists honored her as 'Sportswoman of 2014', category MMA. J. "Skip" Hall is a former mixed martial artist and IBM sales manager.  At 57, "Skip" claimed to be the oldest pro-debuting fighter, and in 2008 at the age of 63 he gained a measure of notoriety as an unusually old combat sports athlete.  He was a participant in the Jasper City Slugfest in August 2006 against former UFC Superfight Champion Dan Severn, and retired in 2009 from active MMA fighting after declaring himself "Oldest Active MMA Fighter in history." A split draw is an outcome in several full-contact combat sports, including boxing, mixed martial arts, and other sports involving striking.  In a split draw, one of the three judges scores the contest in favor of one fighter, another judge scores the contest in favor of the other fighter, and the third judge scores the contest as a draw.  The decision is announced as a draw. Pound for pound is a ranking used in combat sports, such as boxing or mixed martial arts, of who the better fighters are relative to their weight (i.e., adjusted to compensate for weight class).  As these fighters do not compete directly, judging the best fighter pound for pound is subjective, and ratings vary.  They may be based on a range of criteria including "quality of opposition", factors such as how exciting the fighter is or how famous they are, or be an attempt to determine who would win if all those ranked were the same size.  In boxing, the term was historically associated with fighters such as Benny Leonard and Sugar Ray Robinson who were widely considered to be the most skilled fighters of their day, to distinguish them from the generally more popular (and better compensated) heavyweight champions.  Since 1990, "The Ring" magazine has maintained a pound for pound rank of fighters.  ESPN.com has a list for mixed martial artists.  In December 2013, Ronda Rousey became the first woman to appear on the top 10 of a mixed-gender major publication. The Khalid Bin Hamad Al Khalifa Mixed Martial Arts (KHK MMA) is a martial arts organization based in Bahrain.  It was founded under the patronage of His Highness Khalid bin Hamad Al Khalifa for its current CEO and professional MMA fighter Mohammed "The Hawk" Shahid in February 2015.  Fighters competing under KHK MMA banner include: former UFC lightweight champion Frankie Edgar, UFC lightweight contender Khabib Nurmagomedov, UFC lightweight fighter Islam Makhachev, Bellator fighter James Gallagher, 2-time IMMAF champion Jose "Shorty" Torres, former UFC fighter and current Titan FC contender Alex Soto, and current Desert Force fighter Hamza Kooheji.  KHK MMA activities include: coaching pro fighters, developing amateur MMA, promoting martial arts events, fitness gyms, and a sports gear brand. A majority draw is an outcome in several full-contact combat sports, including boxing, mixed martial arts, and others sports involving striking.  In a majority draw, two of the three judges agree that neither fighter won (i.e. tied scorecards), while the third judge indicates one fighter being the clear winner on his/her scorecard.  Thus, the majority of judges see the outcome as even and the result is announced as such, although one judge gave a clear victory on his/her card to one fighter. Mixed Martial Arts Pakistan (or PAK MMA) is the premiere mixed martial arts (MMA) and martial arts promotion based in Pakistan that was created in December 2007 by Bashir Ahmad to promote martial arts (and martial sports such as boxing and wrestling) styles in Pakistan with a particular focus on mixed martial arts competition. Joanna Jędrzejczyk (] ; born August 18, 1987) is a Polish mixed martial artist and former Muay Thai kickboxer who competes in the women's strawweight division of the Ultimate Fighting Championship.  She is the current UFC Women's Strawweight Champion and the third European (and only Polish) champion in UFC history after Bas Rutten in 1999 and Andrei Arlovski in 2005.  As of May 2017, she is the consensus #1 female strawweight, and #1 pound-for-pound female MMA fighter in the world.  She is also currently the #8 pound-for-pound fighter in the UFC mixed gender rankings, making her the top female on the list. Mohammed Shahid (born July 8, 1989) is an entrepreneur and a mixed martial artist from Bahrain.  He is the CEO of KHK MMA and the President of the Bahrain based mixed martial arts organisation, Brave Combat Federation owned and supported by His Highness Sheikh Khalid bin Hamad Al Khalifa.  Mohammed Shahid was the first mixed martial artist from Bahrain to compete in global MMA events.  He was assigned a managerial role to develop mixed martial arts in Bahrain as the CEO of KHK MMA.  Bahrain established a national team alongside bringing global talent to facilitate the growth of MMA in Bahrain. Guy Mezger (born January 1, 1968) is an American martial artist, who competed in professional combat sports including full contact karate, kickboxing, and boxing, but is most recognized as a mixed martial arts (MMA) fighter.  Mezger retired from professional competition on January 25, 2005.  He is associated with Lion's Den and runs their school in Dallas.  Mezger was a champion in mixed martial arts in two different promotions, the UFC and Pancrase.  He holds wins over Tito Ortiz, Masakatsu Funaki, Yuki Kondo, Semmy Schilt, and Minoru Suzuki.
Answer: Pound for pound