Researchers at Virginia Tech wanted to explore whether or not the presence of nitrogen affects the stem weight of red oak seedlings. The stem weights in grams, at the end of 140 days were recorded for the two groups (no nitrogen and nitrogen). The data can be found in theSymbiotic Data. Estimate the true mean difference in stem weights for the two groups using a 90% confidence interval. Source: Walpole, R.,Myers, R. & Ye, K. (2017).Probability and Statistics for Engineers & Scientists. (9th edition). M.A.: Pearson.
Define the parameters that we are estimating. Be sure to include the correct symbol.
Identify the order of subtraction used to create a confidence interval.
Interpret the 90% confidence interval in context.