The Environmental Protection Authority in New South Wales published a paper which
discussed plastic shopping bags. The paper referred to a 2015 Omnipoll survey which showed
64% of NSW respondents supported a total ban on single-use plastic shopping bags
(Environmental Protection Authority, Plastic Shopping Bags: Options Paper, EPA 2016,
accessed 27 April 2018). Assume that a follow-up study is
undertaken to see whether the support for a ban on single-use plastic bags in NSW has
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increased. A random sample of 300 shoppers is surveyed and 205 support a ban on single-use
plastic shopping bags.
a. At the 0.05 level of significance, use the six-step hypothesis-testing method to try to test
whether the proportion of shoppers using alternative bags is significantly higher.
b. Use the five-step p-value approach. Interpret the meaning of the p-value.
c. Repeat (a) and (b) using a sample size of 1,000 and the same sample proportion.
d. Discuss the effect that sample size had on the outcome of this analysis and, in general, on
the effect sample size plays in hypothesis testing.