Basic sampling and statistics using systat: Bring your laptop to class, if you can.  If you don't have a laptop, or can't bring it, bring your calculator with statistical functions.  I'll provide a copy of a statistical program you can load on your computer and use throughout the semester.  I will have a few laptops available in lab as well. I'll provide a hand-out from the lab manual you don't have yet that will provide background on basic stats.  We will meet in the lab.  

Tuesday Lab:

Data for the Tuesday lab for manual entry.  Each line in the data set below is one table's mean fruit set for either the primary shoots (1) or the secondary shoots (2).  There are six lab tables, each measuring 10-12 shoots. 

fruitset	shoot type
0.070	1
0.049	1
0.03	1
0.036	1
0.043	1
0.131	1
0.136	2
0.257	2
0.048	2
0.287	2
0.118	2
0.294	2

 

Grading will be based on the following criteria: (1) adherence to the form requested (2) are the questions directly addressed? (3) are the results of data analysis clearly explained in the answers, demonstrating that you understand t-tests? (4) are the results interpreted correctly with significant patterns in the results identified?  (5) are figures clear with a complete caption that does not require a reader to guess or read the text to understand the figure?  All group members may attach their individual reports to the same set of SYSTAT results and bar graphs.

 

Turn in during lab next week the answers the the following questions.  Your answers need to be word processed, and the questions should be listed by number with the question written out (cut and paste works well).  If it is more than one page long, staple it.  Each lab table group should turn in their papers bound together with a paper clip and attached to one set of figures and t-test results.  

1.   What hypothesis (or question) did you address?  Ecologists prefer simply worded hypotheses or questions, and you don't need to state the null hypothesis.  Include enough information that the hypothesis or question makes logical sense.  For example: Do grasshoppers collected in fertilized fields grow larger and thus weigh more than grasshoppers collected from the unfertilized nature reserve?

2.  Does your table’s data support or refute your hypothesis? Explain. Provide evidence in the form of reference to a graph showing the means and reference to the statistical tests you ran.  You can’t answer this question without reference to your t-test and p values.  Include a bar graph and statistical tests you refer to.

3.  Does the class data support or refute your hypothesis? Explain. Provide evidence in the form of reference to a graph showing the means and reference to the statistical tests you ran.  You can’t answer this question without reference to your t-test and p values.  Include the graph and statistical tests you refer to.

4. Explain the differences in the data (use mean, n, and the standard deviation) from your table (n=10) and the whole class data (n=6).  Which more accurately reflects what is already known about this plant?  Larson, Fowler, and Walker published a paper (Larson et al. 2002) that surveyed fruit sets in 7 different sites in Arkansas and found that primary shoot fruit set averaged 13% + 4.1 (mean + SE) on primary shoots and 23 + 6.7 on secondary shoots. 

 

Thurday Lab:  Here is data for each table for nodes and internodes...I hope you have lats.

Please follow the questions above for the tuesday lab, with the exception of the relationship to known information in question 4.  For that you may use a recent graduate student thesis that found internode lengths of climbing shoots to be 9.45 + 0.20 (mean + SE) while they were 10.48 + 0.24 for ground shoots (Walter, T. 2006).

Friday Lab:

Use the questions for the Tuesday lab.  You should use your own table's data to answer question 2 and your lab's mean based on the 6 tables for question 3 and 4.