Problem 1: In January 2006, Dan Donato and co-authors J.B. Fontaine, J.L. Campbell, W.D. Robinson, J.B. Kauffman, and B.E. Law published a short Science article (vol 311, p.352) reporting, essentially, that measure seedlings after a natural fire in Oregon indicated that it seemed better for seedlings not to salvage log. That is, there was a greater decrease in the number of seedling in the logged areas between 2004 and 2005 than in the unlogged areas. The fire that occurred in 2002 was named the Biscuit fire and the logging occurred in between the record of seedling numbers given in the table below.
Later in 2006, after his article was published, Dan was hauled in front of a congressional committee, in part to defend his statistical analysis. Congressman Baird disputed Dan's statistical techniques claiming that others (2-sample t-tests), more appropriate for the analysis of these data, indicated no significant difference in logged versus unlogged areas.
Analyze these data yourself and write a report, either defending Dan's and his co-author's claim that logging hurt seedling production or defending Congressman Baird's contention that there is no significant difference. Think about what the appropriate null and alternative hypotheses should be - these are formed before seeing the data. Note that before these data were published, it was widely believed that logging should be beneficial for seedling rejuvenation. Defend your choice of statistical test - preferably in language that a congressman could understand.
Plot seedlings_2004 seedlings_2005 treatment 1 298 164 logged 2 471 221 logged 3 767 454 logged 4 576 141 logged 5 407 217 logged 6 1534 224 logged 7 2423 349 logged 8 1697 1388 logged 9 1137 646 logged 10 288 220 unlogged 11 622 747 unlogged 12 300 260 unlogged 13 888 584 unlogged 14 1448 1566 unlogged 15 1425 626 unlogged 16 2349 1924 unlogged