A scientist wants to measure the effect of acid rain on a species of plant. In his laboratory, he creates an artificial environment, which mimics the natural environment of the plant. He inserts 2 groups of the plant species into this environment. On one group he allows synthetic acid rainwater to fall, and on the other group he allows non-acidic, synthetic rainwater to fall. This process is repeated 10 times over the period of 50 days. What type of data will he measure?

In this experiment the scientist will measure different variables such as height of the plants, number of leaves or thickness of the stem among others, to compare the different results in the two environments (the one that has synthetic acid rainwater and that doesn't), so that he can determine the effect of the acid rain on a species of plants.

All the data that he will collect will be numbers for example in the day number 1 he measures the height of both plants and he gets that the plant that is in the environment with synthetic acid rainwater measures 1 cm while the one that is in the non-acidic synthetic rainwater measures 2 cm.

As the answers are numbers you can descard the nominal and the ordinal types of measures, and because the diference between the number matters (you know that 2 is bigger than 1) and also the zero means no growing so it determines the value scale, you can descard the interval type of measure, leaving the ratio measure which is a quantitative (the answer has numbers) type of measure in which you can define the order, the exact value between units and you can define an absolute zero.