Question

Data was collected in order to investigate the effect of temperature on the yield of a chemical process. Temperatures were set at eight specific levels, and the yield was determined for five replications at each level 4. Identify the response variable and the predictor variable. Explain your reasoning. Describe the two sources of variation (variation due to regression and variation about the regression) in terms of this particular problem (using the variables described above). In this particular case, are we investigating for association or causation? Defend your answer. a. b. c.

Answer 1

a. response variable=yield of chemical process

Predictor variable=temperature

b. Variation due to different levels of temperature (i.e. variation due to regression) and variation due to error (i.e. random variation or variation about the regression).

c.  When investigators find a correlation, which can also be called an association, they found a relationship between two, or more, variables.

The causation means that the investigators found that changes in one variable they measured directly caused changes in the other.

Here we investigate the effect of different levels of temperature on the yield of a chemical process so we investigate for causation.