A coastal research team programs a drone to photograph one of eight marked rock pools after each battery change. The random target number is intended to red...
Question 1 Report
A coastal research team programs a drone to photograph one of eight marked rock pools after each battery change. The random target number is intended to reduce observer bias when choosing pools for a biodiversity survey. The drone records its target in a file before flying. On one day, target 4 is chosen three times and target 7 is not chosen at all. A volunteer suggests replacing the random command with a cycle through the pool numbers.
(a) Explain why random target selection can reduce observer bias in this investigation. [1]
(b) When assessing the volunteer's observation, explain why the results from one day are not enough to judge whether the command is fair. [2]
A fitness app creates a short circuit-training session from eight exercise cards. At the start of each round, a random card number is generated and the exercise instructions are displayed. The designer wants no exercise to appear more than once in a session of eight rounds. The current skeleton program simply uses RANDOM(1,8) at every round. During a test, lunges are selected twice, while skipping is never selected. The designer considers shuffling the cards into a new list before the session starts.
(a) Explain why repeated use of RANDOM(1,8) can produce duplicate exercises. [1]
(b) When a shuffled list is used, explain how the main program can display eight different exercises. [2]
(c) Explain one benefit of generating a new shuffled list for a new player. [2]
Answer Details
Rock-pool selection
(a) Random selection reduces observer bias because the observer is not deliberately choosing particular rock pools. [1]
(b) A small number of random trials can give uneven results, such as one pool occurring three times and another not occurring. Many more selections are needed before comparing frequencies with the expected equal chances, so one day is not enough to judge fairness. [2]
Exercise-card selection
(a) Each use of RANDOM(1,8) can select a number selected previously. Thus repeated random generation can produce duplicate exercises. [1]
(b) Put all eight exercise cards into a list in random order, then use each list item once from the first item to the last. Each of the eight displayed exercises will then be different. [2]
(c) Generating a new shuffled list changes the order for a new player. This improves variety and reduces predictability. [2]
Download The App On Google Playstore
Everything you need to excel in your exams
