Chapter 18 Quiz: Tracking Data Analytics

Instructions: Select the best answer for each question. Each question has exactly one correct answer unless otherwise stated.

Question 1. What is the typical frame rate of optical tracking systems used in major European soccer leagues?

A) 5 Hz B) 10 Hz C) 25 Hz D) 100 Hz

Question 2. A tracking system operating at 25 Hz records data for a 90-minute match. Approximately how many frames of data are generated?

A) 13,500 B) 54,000 C) 135,000 D) 540,000

Question 3. Which of the following is NOT a standard preprocessing step for raw tracking data?

A) Smoothing with a Savitzky-Golay filter B) Interpolation of missing positions C) Conversion to polar coordinates D) Coordinate normalization to a standard pitch size

Question 4. The central finite difference formula for velocity is preferred over the forward difference because:

A) It requires fewer data points B) It reduces the truncation error from $O(\Delta t)$ to $O(\Delta t^2)$ C) It eliminates all measurement noise D) It does not require knowledge of the time step

Question 5. According to the standard speed zone definitions in this chapter, a player moving at 8.2 m/s would be classified as:

A) Running B) High-speed running C) Sprinting D) Jogging

Question 6. The typical total distance covered by a central midfielder in a 90-minute match is approximately:

A) 9.0 -- 10.5 km B) 11.0 -- 12.5 km C) 13.5 -- 15.0 km D) 16.0 -- 17.5 km

Question 7. What does the tangential component of acceleration represent?

A) Change in direction of movement B) Change in speed (speeding up or slowing down) C) The gravitational force on the player D) The centripetal force during turning

Question 8. In the metabolic power model, what does the "equivalent slope" represent?

A) The actual gradient of the pitch surface B) A mapping of horizontal acceleration to an equivalent uphill gradient C) The ratio of vertical to horizontal velocity D) The efficiency of the player's running stride

Question 9. Which metric is considered the most sensitive indicator of fatigue within a match?

A) Total distance covered B) Average speed C) High-speed running distance (HSRD) D) Number of passes completed

Question 10. The team centroid is computed as:

A) The position of the player closest to the center of the pitch B) The median of all player positions C) The arithmetic mean of all outfield player positions D) The position of the ball

Question 11. What does the stretch index measure?

A) The maximum distance between any two players on the team B) The average distance of all outfield players from the team centroid C) The ratio of team length to team width D) The total distance covered by the team in a match

Question 12. In the context of Voronoi tessellation applied to soccer, a player's Voronoi cell represents:

A) The area where the player has been during the match B) The set of pitch locations closer to that player than to any other player C) The player's expected threat zone D) The area within the player's sprint range

Question 13. A team's convex hull area typically increases when the team is:

A) Defending B) In possession (attacking) C) Playing with 10 men after a red card D) Protecting a lead in the final minutes

Question 14. In correlation-based team synchronization, a value of $S_x \approx 1$ along the $x$-axis indicates that:

A) All players are stationary B) All players are moving in the same direction along the $x$-axis simultaneously C) Players are moving randomly D) The team is in a compact formation

Question 15. The Acute-to-Chronic Workload Ratio (ACWR) "sweet spot" for balancing performance and injury risk is generally considered to be:

A) 0.3 -- 0.6 B) 0.8 -- 1.3 C) 1.5 -- 2.0 D) 2.0 -- 3.0

Question 16. Transient fatigue refers to:

A) The progressive decline in physical output across a full match B) Temporary performance decrements following intense passages of play C) The long-term fatigue accumulated over a season D) Fatigue caused by travel and jet lag

Question 17. Which of the following is a challenge when synchronizing event data with tracking data?

A) Both data types use identical timestamps B) Event data has higher temporal resolution than tracking data C) Annotation delays can cause 1--2 second timing errors in event data D) Tracking data does not contain ball positions

Question 18. In a pitch control model, a player's influence at a point on the pitch typically depends on:

A) Only the player's position B) The player's position, velocity, and estimated time-to-reach the point C) Only the player's maximum speed D) The player's jersey number

Question 19. The PPDA metric (Passes Per Defensive Action) is primarily used to quantify:

A) Passing accuracy B) Pressing intensity C) Sprint performance D) Goalkeeper distribution

Question 20. What is the primary advantage of the EWMA method for computing ACWR over the simple rolling average method?

A) It requires less data B) It assigns higher weight to more recent sessions C) It eliminates the need for a chronic window D) It always produces lower ACWR values

Question 21. When integrating tracking and event data, which of the following features can tracking data add to a shot event that event data alone cannot provide?

A) The outcome of the shot (goal, saved, missed) B) The positions of all defenders at the moment of the shot C) The type of shot (header, left foot, right foot) D) The name of the player who took the shot

Question 22. A player's work rate is 130 m/min in the first half and 108 m/min in the second half. The percentage decline is approximately:

A) 10.3% B) 14.5% C) 18.9% D) 22.4%

Question 23. Which technology is most commonly used for match-day tracking in top European leagues?

A) GPS wearable devices B) Optical tracking systems C) Radio-frequency identification (RFID) D) Radar systems

Question 24. In the context of pressing analysis, counterpressure intensity considers:

A) Only the number of defending players near the ball B) The collective speed and direction of defending players relative to the ball C) The total distance covered by the defending team D) The number of fouls committed

Question 25. Which of the following statements about metabolic power is FALSE?

A) It accounts for both speed and acceleration in energy expenditure estimation B) It was originally derived from linear running on flat surfaces C) It accurately models the energy cost of deceleration (eccentric muscle actions) D) It uses the concept of an "equivalent slope" to map acceleration to energy cost

Answer Key

  1. C --- Optical tracking systems in major leagues typically operate at 25 Hz.

  2. C --- $25 \text{ frames/s} \times 90 \text{ min} \times 60 \text{ s/min} = 135{,}000$ frames.

  3. C --- Conversion to polar coordinates is not a standard preprocessing step. Smoothing, interpolation, and coordinate normalization are standard.

  4. B --- Central differences have truncation error $O(\Delta t^2)$, an order of magnitude better than forward differences at $O(\Delta t)$.

  5. B --- 8.2 m/s falls in the high-speed running zone (7.5 -- 9.0 m/s).

  6. C --- Central midfielders typically cover 13.5 -- 15.0 km per match.

  7. B --- Tangential acceleration reflects changes in speed; normal acceleration reflects changes in direction.

  8. B --- The equivalent slope maps horizontal acceleration to an equivalent uphill gradient for energy cost estimation.

  9. C --- HSRD is more sensitive to fatigue than total distance, as players maintain total distance by substituting high-intensity running with low-intensity movement.

  10. C --- The team centroid is the arithmetic mean of all outfield player positions.

  11. B --- The stretch index is the average distance of outfield players from the team centroid.

  12. B --- A Voronoi cell contains all points closer to that player than to any other.

  13. B --- Teams typically expand their shape when in possession.

  14. B --- High correlation means players are moving together in the same direction.

  15. B --- The ACWR sweet spot is 0.8 -- 1.3 (Gabbett, 2016).

  16. B --- Transient fatigue is a temporary performance decrement after intense effort, distinct from progressive match fatigue.

  17. C --- Annotation delays of 1--2 seconds are a common synchronization challenge.

  18. B --- Pitch control models consider position, velocity, and time-to-reach.

  19. B --- PPDA quantifies pressing intensity by measuring how many passes the pressing team allows before making a defensive action.

  20. B --- EWMA assigns exponentially higher weight to more recent sessions.

  21. B --- Tracking data provides the positions of all 22 players, including defenders not directly involved in the event.

  22. C --- $(130 - 108) / 130 \times 100\% = 18.9\%$.

  23. B --- Optical tracking systems (TRACAB, Second Spectrum, Hawk-Eye) are the standard in top European leagues.

  24. B --- Counterpressure intensity considers both the speed and direction of movement relative to the ball.

  25. C --- Metabolic power does NOT accurately model deceleration energy costs; this is a known limitation.