Which one of the following statements is not true for the term "rational subgroups?" The chance of observing differences within a sample should be high. Samples of consecutive measurements over a short period of time should be used Samples should be chosen to be as homogeneous as possible. Question 12 (4 points) Which one of the following statements is not true for assignable causes of variation? It accounts for majority of the observed variation It is usually economical to correct It appears sporadically It is the result of special causes It disrupt the random pattern of the sample data Question 13 (4 points) The manager of a plant producing RFID scanners would like to know if defective scanners are related to certain time of the day during the first shift. A tool that would be most appropriate is a Scatter diagram Run chart Pareto chart Cause-and-effect diagram