Which of the following steps should be taken if one bottling line is found to produce a main effect but filling temperature has no effect?

Investigating bottling line differences is crucial when one bottling line produces a main effect while another variable, such as filling temperature, shows no effect. This indicates that the variability in the bottling line itself may be influencing the outcome significantly. Understanding the specific characteristics or processes of the bottling line that produces a change can provide insights into why the filling temperature does not contribute to the main effect.

By focusing on the differences in bottling lines, one can analyze factors such as equipment settings, operator skills, or environmental conditions that might be unique to the productive line. This can lead to more informed decisions regarding improvements or adjustments needed in the bottling process overall.

Other options would not appropriately address the observed effect. Simply repeating the experiment on the same line may not yield new insights if the same factors are at play. Conducting an analysis of variance on the temperature treatments wouldn't be beneficial since you've established that temperature has no effect in this scenario. Lastly, determining interaction effects between bottling lines might be unnecessary when the primary goal is to understand the differences that directly affect the main effect observed.