Bio 156 -pattern analyses name

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BIO 156 -PATTERN ANALYSES Name _______________________________

Practice PTS ______________________

EXAM #2 part I (46 pts)
Multiple Choice (4 pts each - 24 pts)

For each question, choose the appropriate analysis and place the corresponding letter in front of the question. Answers may be used more than once, but only one answer per question.


Goodness of Fit-Binomial


Goodness of Fit-Poisson


Mean and variance - sample


Median and IQD


2x2 Test of Independence


RxC Test of Independence


Log Linear Analysis


Pearson Product Moment correlation


Principle Components analysis (PCA)


Multidimensional Scaling (MDS)

____ 1. You would like to characterize students for an upcoming study. You have created a survey with 50 yes/no type questions.

____ 2. You are doing habitat reclamation and you want to have an idea if your efforts are succeeding. You have measured similarity between the restored habitat and a natural site over time. If your efforts are succeeding there should be a negative relationship between similarity and time.
____ 3. You are studying the distribution of the small brown bat, Myotis lucifugus. You suspect there might be subpopulations that have slight differences in body form and you want to see if bats could be grouped by body form . You have captured several specimens in various habitats and have measured lengths of the bones in their wings along with various skull measurements.
____ 4. You suspect that the distribution of a species of intertidal snail, Tectura scutum, may be affected predatory seastars (Pisaster ochraceus), rock crabs (Cancer antennarius), anemones, and/or tidal zone. You randomly select 100 sites and, at each, you record whether the site is in the low, mid or upper intertidal zone, and the presence or absence for each of the following: T. scutum, P. ochraceus, C. antennarius and anemones.
____ 5. You suspect that a species of plant may be alleopathic, a chemical process that a plant uses to keep other plants from growing close to it. You randomly select 40 sites and, at each site you use a circular plot technique to measure abundance of the plants.
____ 6. You want to know if bobcats and coyotes tend to avoid each other. You randomly select 200 locations and, at each, record whether or not bobcat scat are present and whether or not coyote scat are present. You are not interested in seeing if the either proportion of bobcat scats present or absent or the proportion of coyote scats present or absent is different from 50/50.

Short Answer (4 pts)

  1. MDS is a technique that produces an ordination such that the original distances between cases are conserved. Give a brief explanation of how it works (4 pts)

Problems (18 pts)

PROBLEM 1: You are interested in determining if there is a relationship between the color morph (Brown, Black or Orange) of the ochre seastar, Pisaster ochraceus, and the presence or absence of mussels. Assume that you want to take 90 observations. Further assume that you only want to sample on rocks and not on sand. The tidal area looks like that in Figure 1. Questions 8 refers to this problem.

  1. Specify a sample design to address this problem that would take care of both unknown and known bias. Be specific about how you would locate sites. READ the problem carefully! (4 pts)

  1. Compute the Bray-Curtis similarity measure for the following data: Your data are specified in Table 1. Show your work! (2 pts)

Table 1: Data for similarity computation

Site A

Site B













PROBLEM 3 (5 pts): You are studying the distribution of two limpets species, Tectura scutum and Lottia pelta. You want to see if there is a negative association between the two species which, if present, would be evidence for a possible competitive interaction. You randomly selected 373 sites in the rocky-intertidal region. At each site, you specified the tidal zone (low, medium or high tidal zone), whether or not T. scutum was present and whether or not L. pelta was present. Alpha for this experiment is 0.025. The analysis is presented in Figures 2 and 3. Questions 10-12 refer to this problem.

  1. What is the fully saturated model for this problem? (1 pts)

  1. In the following table, specify all terms of the model, the p values for those terms (3 decimal places) and whether or not the terms are important. (7 pts)

Table 2: Significance of effects in the loglinear analysis of the limpet data.




  1. Circle the sub-table(s), A, B, C, D, E, F or G in Figure 3 that you would need to graph for the limpet analysis (Figure 2). (4 pts)

_____________ pts off page

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