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BIOL 361 Assignment 3 Marking Scheme (2009)
TOTAL out of 85 marks
Introduction [8 marks]

Identify the topic of the study (if sewage from the City of Waterloo has detrimental
effects on ecological health of the river. There are >20,000 students attending two
local universities who arrive en masse in early September, thus providing an
opportunity to assess if changes in the load of human waste exerts effects on the Grad
River) [
2 marks
], including verbal statement of hypotheses tested [2 marks each for
the tests indicated below [
= 6 marks
]]
1way ANOVA: to test the hypothesis that mean abundance of chironomid larvae differs
among the three weeks of the study at the downstream site on the Grand River [2 mark]
2way ANOVA: to test the hypothesis that there an interactive effect of the week of
sampling and the location of the sampling site (upstream, downstream) on the abundance
of chironomid larvae in the Grand River [2 marks]. If there is no significant interaction,
we will test the claim that the mean abundance of chironomid larvae differs due to each
of the main factors (week of study, sample site) [2 marks]
Methods [20 marks]

[
4 marks
] Must present methods in sufficient detail to allow someone else to repeat
the study and to assess if the experimental design is appropriate/adequate.

Must identify alpha (in Intro or Methods  or at least somewhere) [1 mark]

How were samples randomly collected, or representative of the population, How
was each subject selected independently from the population. [3 mark]

[
16 marks
] clear statements of hypotheses and statistical tests:
1 (1way) & 3 (2
way) [4 tests @ 4 marks each]
Use oneway ANOVA
to test Ho:
μ
week1
=
μ
week2
=
μ
week3
, where
μ
= the mean abundance
of chironomid larvae at each of three sampling dates in subsequent weeks (Aug. 31, Sept.
7 and Sept. 14 of 2004) on submerged rocks at a site downstream of the City of
Waterloo’s wastewater plant in the Grand River. H1: mean abundance differs for at least
one of the sampling dates.
Use twoway ANOVA for three tests:
Test 1:
Ho: there is no interactive effect of the week of sampling and the location of the
sampling site (upstream, downstream) on the mean abundance of chironomid larvae on
rocks in the Grand River
Hi: there an interactive effect of the week of week of sampling and the location of the
sampling site (upstream, downstream) on the mean abundance of chironomid larvae in
the Grand River
1
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View Full DocumentTest 2 – Ho:
μ
week1
=
μ
week2
=
μ
week3
, where
μ
= the mean abundance of chironomid larvae
at each of three sampling dates in subsequent weeks (Aug. 31, Sept. 7 and Sept. 14 of
2004) on submerged rocks in the Grand River.
H1: mean abundance differs for at least one of the sampling dates.
Test 3  Ho:
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 Winter '08
 Hall

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