Bio 009:  Science as a way of knowing, Fall 2007

Problems for quiz 2

1.  In each of the following examples, identify all of the common types of error (sampling error, bias, human/technical error, rounding) that are present.  What aspects of Ideal Data (protocol, rounding, random, replicates, blind, standards) would reduce or eliminate the problem(s)?

A.  converting numerical scores to letter grades

B.  Proponents of rewriting the Endangered Species Act insist that most decisions to list organisms are based upon faulty data and most species are not helped by listing.  To support their claims, they point to the low rates of delisting of endangered species but ignore the large number of species that, while not delisted, have recovered from near extinction.

C.  Losey and his colleagues “eyeballed” the amount of Bt-trangenic corn pollen that they placed on milkweed leaves being fed to the Monarch butterfly caterpillars.

D.  In the Harvard-run “aspirin study”, male Caucasian doctors were randomly assigned to receive either an aspirin a day or a placebo.  The results, after 10 years, showed a clear benefits of taking aspirin in reducing the risk of heart attack.  However, later studies showed no such benefits for either women or African-American males.

E.  There is a species of butterflies that is distributed across North America east of the Rockies and south of the Artic circle.  A lepidopterist when establishing a laboratory colony of butterflies collects five adult females from the old field near Amherst, and uses the offspring of these butterflies to determine the variety of plants eaten by the larvae.

2.  In each of the following methods statements, read the text carefully.  Identify the study as observational or experimental.  Then mark in the margin the location, if present,  each of the five aspects of ideal data (protocol, random, replicates, blind, standards). 

A.  “We raised female mice of two inbred strains…and their F1-hybrids in three different laboratories in small, standard cages or large, enriched cages.  When the mice reached adulthood, we subjected them to four of the nost common behavioral tests used in drog screening…  Each laboratory independently ordered three batches of 48 mice to run three independent replicates for each test (total number of mice was 432).”

B.  “The report by EduMetrics…studied 92 children in Washington, D.C., schools.  The students were required to read a challenging passage about the rain-forest;  then, pretending to be a creature who lived there, they had to write a letter to a desert-dwelling creature.  …
    Before an 8-week engagement with kinetic City, most of the children scored 0, and only two got top marks.  Afterward, most completed the assignment satisfactorily and 28 children – 30% - got top scores”.

3.  Considering each of the following statements,

(i) restate it, if necessary, as an hypothesis

(ii) is it testable (can you conceive of a do-able study that could potentially result in data that would result in rejection of the hypothesis)?

(iii) if testable, would you use an observational or experimental study?

(iv) what kinds of error would the study be prone to?

(v) what aspects of ideal data would be crucial to include?

A.  The rediscovery of Mendel’s laws of genetics caused rapid acceleration of crop development.


B.  Farmers in Mexico that plant modern hybrid corn have higher yields than farmers who plant traditional corn strains.


C.  Introduction of modern rice varieties has greatly reduced the diversity of traditional rice that are being planted in Asia.


D.  Pollen flow from fields of transgenic canola is moving the transgenes into non-transgenic canola plants, threatening the “organic” status of many organic farmers in Canada.