How percentages are used in sports

Transcription

1 How percentages are used in sports By Gale, Cengage Learning, adapted by Newsela staff on Word Count 887 Level 1060L Image 1. Kevin Durant goes up for a dunk against the Phoenix Suns in 2018, in Oakland, California. Durant is one of seven players in history to join the club: players who have shooting percentage at or above 50% for field goals, 40% for threepointers and 90% for free throws during an NBA season. Photo by: Marcio Jose Sanchez/AP Photo Percentages have many uses in sports and in sports media. There is a seemingly limitless number of ways in which commentators use statistics based on percentage calculations. This article is available at 5 reading levels at 1

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3 For example, the ".300 hitter" is a description applied to a hitter in baseball who is consistently good, whereas ".400 hitters," like Ted Williams and Ty Cobb, are considered legendary. A 90% free-throw shooter in basketball has a similar reputation. Sometimes percentages can be a useful indicator of a player's performance. Other times, they are just there to add minor details to the story. Good coaches are able to tell the difference. For instance, say Amanda and Claire are members of their high school basketball team. Their coach wants to select the most valuable player for the season. Amanda scored 160 total points, making 62 of point shots attempted, 6 of 10 3-point shots attempted and 18 of 21 free throws attempted. She played 17.5 minutes each game. Claire scored 322 total points, making 125 of point shots attempted, 5 of 22 3-point shots attempted, 57 of 81 free throws attempted. She played 28.8 minutes played per game. The team scored a total of 887 points on the season. The 2-point shooting of each player can be compared by calculating the shooting percentage. Amanda made 62 of the 108 shots she attempted, or 57.4%. Claire made 125 of the 341 shots she attempted, or 36.7%. Their 3-point and free-throw shooting can be compared in the same way. Amanda made 6 shots out of 10 she attempted, or 60%. Claire made 5 of 22, or 22.7%. Amanda made 18 of 21 free throws for 85.7%. Claire made 57 of 81 for 70.4%. Amanda's shooting percentages are all better than Claire's. Claire scored more points and played more minutes per game, though. For Amanda, 160 points scored out of 887 team points scored means she scored 18% of the team offense. For Claire, 322 points scored out of 887 team points scored is equal to 36.3% of the team offense. Further, Amanda produced her 18% of the team offense in 17.5 minutes per game. Claire produced her 36.3% of the team offense in 28.8 minutes per game. There are certain hard conclusions that the coach may have reached based upon these percentage calculations. Amanda seems to be a more accurate shooter in every aspect. The coach may create more opportunities for Amanda to shoot next season. However, other information can help to better understand the percentages. Perhaps Amanda is much worse in other areas, like passing. Maybe other teams felt Claire was the team's best player and focused more of their defense on her, which would make her shooting percentages more notable. In baseball, a strong hitter will be referred to as a ".300 hitter," meaning a player who gets a hit at least 30% (or 0.300) of the time he or she steps up to the plate. Baseball has many other useful statistics too, like "on-base percentage." It measures how often a batter reaches a base. Batting average calculates only hits, but on-base percentage accounts for walks and other ways to get on base. The percentage is calculated by dividing the total number of times on base by the total number of plate appearances. This article is available at 5 reading levels at 3

4 North American football also has many statistics, like a quarterback's completion percentage. Each time the quarterback throws the ball and someone catches it, it is called a completion. A quarterback's completion percentage is found by dividing the number of passes completed by the number of passes thrown. However, this percentage can be deceiving without additional information. A quarterback who throws 80% of his passes for completions, but never throws a pass for a score, is unlikely to be as successful as the 50% passer who throws for 20 touchdowns in a season. Tournament Percentages And RPI There are hundreds of college sports teams, and it is impossible to have them all play one another in a given season. To deal with this problem, statistical tools were developed to weigh the relative abilities of teams that would not necessarily meet. These tools are used in tournaments or championships to determine who was the best team that year. In American college basketball, hockey and football, tournament selection is made using what is known as the RPI, or ratings percentage index. In college basketball, RPI is defined as: Team winning percentage 25% + opponents winning percentage 50% + opponents' opponents winning percentage 25%. This article is available at 5 reading levels at 4

5 If a team had a record of 16 wins and 12 losses in a season, its team winning percentage would be 57.14%. Say the average of all its opponents' winning percentages was 53.05%. Say the average of the winning percentages of all opponents' opponents was 49.1%. The RPI calculation would be 57.14/100 25/ /100 50/ /100 25/100 = A team will have a higher RPI if the team combines its own success with an ability to beat strong opponents that have themselves played against strong teams. Therefore, a team can have a worse record than a rival but may be ranked higher because it played tougher opponents. The percentage calculation is at the root of any RPI. This article is available at 5 reading levels at 5

6 Quiz 1 Read the selection from the Introduction [paragraphs 1-9]. Amanda seems to be a more accurate shooter in every aspect. The coach may create more opportunities for Amanda to shoot next season. However, other information can help to better understand the percentages. Perhaps Amanda is much worse in other areas, like passing. Maybe other teams felt Claire was the team's best player and focused more of their defense on her, which would make her shooting percentages more notable. Which conclusion is BEST supported by this selection? (A) (B) (C) (D) Amanda and Claire have never played on the same team before this, so they do not know how to help each other. Other teams always study the percentages of their opponents in order to decide which players to focus defense on. Coaches can rely on shooting percentages alone to make decisions about which of their players are best and should play often. Additional information about players' games and skills is needed to fully understand what percentages say about them. This article is available at 5 reading levels at 6

7 2 Read the following statement. Using percentages, it is even possible to figure out how to compare teams that never play against each other. Which sentence from the article provides the BEST support for the above statement? (A) (B) (C) (D) Percentages have many uses in sports and in sports media. There is a seemingly limitless number of ways in which commentators use statistics based on percentage calculations. A quarterback who throws 80% of his passes for completions, but never throws a pass for a score, is unlikely to be as successful as the 50% passer who throws for 20 touchdowns in a season. There are hundreds of college sports teams, and it is impossible to have them all play one another in a given season. To deal with this problem, statistical tools were developed to weigh the relative abilities of teams that would not necessarily meet. A team will have a higher RPI if the team combines its own success with an ability to beat strong opponents that have themselves played against strong teams. Therefore, a team can have a worse record than a rival but may be ranked higher because it played tougher opponents. 3 Which option accurately compares how the images impact the reader's understanding of percentages in sports? (A) (B) (C) (D) Images 1 and 2 provide examples of players who are statistically remarkable, and Images 3 and 4 show how to figure out common sports percentages. Images 1 and 2 provide examples of players who were able to use statistics successfully, and Images 3 and 4 provide details about the specific numbers they used. Images 1 and 2 provide examples of players in different sports that use percentages, and Images 3 and 4 illustrate the math used in their specific sports. Images 1 and 2 provide examples of players that have some of the most impressive statistics in their sports, and Images 3 and 4 illustrate how they figured out which percentages were important. This article is available at 5 reading levels at 7

8 4 Which selection from the article is BEST illustrated by Image 3? (A) (B) (C) (D) For example, the "300 hitter" is a description applied to a hitter in baseball who is consistently good, whereas "400 hitters," like Ted Williams and Ty Cobb, are considered legendary. In baseball, a strong hitter will be referred to as a "300 hitter," meaning a player who gets a hit at least 30% (or 0.300) of the time. It measures how often a batter advances to first base. Batting average calculates only hits, but on-base percentage accounts for walks and other ways to get on base. The percentage is calculated by dividing the total number of times on base by the total number of plate appearances. This article is available at 5 reading levels at 8