Theory-based approach (one-proportion z-test) In Question 5(a), you probably described the shape of the null distribution using words such as bellshaped, symmetric, or maybe even normal. You have seen many null distributions in this chapter that have had this same basic shape. You should have also noticed that the null distributions have all been centered at the hypothesized value of the longrun proportion used in the null hypotheses. You probably could have predicted that your null distribution was going to be somewhat bellshaped and centered at 0.50. You probably would have a harder time predicting your null distribution's variability [standard deviation), but this too can be predicted in advance, as we will see shortly. We can use mathematical models known as normal distributions (bellshaped curves} to approximate many of the null distributions we have generated so far in this text. 'When rules and theories are used to predict what the value of the standardized statistic and pvalue would be if someone did simulate, we call the approach a theory-based approach. The normal distri bution provides a second way, in addition to simulation, to approximate a pvalue. 6. Check the box next to Normal Approximation in the applet. Does the region shaded in blue seem to be a good description (model) of what we actually got in the simulation? Validity conditions for theory-based approach The normal approximation to the null distribution is valid whenever the sample size is reason ably iarge. One convention is to consider the sample size to be large enough whenever there are at least 10 observations in each category. 1'. According to this convention, is the sample size large enough in this study to use the normal approximation and theorybased inference? Justify your