Seed Germination Experiment Design

A research team is investigating how varying the amount of water affects the germination rate of seeds. They set up four groups of seeds, watering them with different amounts of water: 10 mL, 20 mL, 30 mL, and 40 mL per day. After a week, the researchers count the number of seeds that have germinated in each group. To assess their results, the researchers need to determine the best way to analyze the data collected.

This study aims to establish a correlation between the amount of water and seed germination rates. What is the most crucial element that the research team should consider while designing their experiment?