12. a researcher wants to know the average gr...

12. a researcher wants to know the average growth of a certain plant one week after germination. the greenhouse where he grows the plants has 12 trays with 36 plants on each tray. he picks one tray from the greenhouse and measures the heights of each plant. the results are shown in the dot - plot. plant height frequency 1.5 2 2.5 3 3.5 4 4.5 height (in.). when analyzing the data, he sees that the heights of the plants are clustered around 2 in. could this be the result of bias in his sampling method? explain. see example 2 19. a newspaper hires a polling company to determine the level of support in the county for raising property taxes in order to increase funding for local schools. the polling company calls phone numbers chosen at random from a phone number registry between the hours of 5:00 p.m. and 7:00 p.m. what are some potential sources of bias in this sampling method?

Answer

# Answer: 12. Yes, this could be the result of bias in his sampling method. 19. Some potential sources of bias include: People without land - lines or not home between 5:00 P.M. and 7:00 P.M. are not represented; those with strong opinions about property taxes may be more likely to answer. # Brief Explanations: 12. By only sampling one tray out of 12, the sample may not be representative of all plants in the greenhouse. There could be differences between trays that affect plant height. 19. Sampling only from a phone number registry misses those without land - lines. Also, the time of calling may exclude certain groups (e.g., those at work or running errands) and self - selection bias may occur as those with strong views are more likely to respond.