Chemistry Reference
In-Depth Information
Table 8.3
Effect of ripeness at purchase on texture of early-season peaches when stored at different
temperatures. Sensory juiciness was evaluated on a 150 mm scale with a higher value correspond-
ing to a firmer peach as perceived in the mouth. Values in the same column followed by a different
lower-case letter or in the same row or followed by a different upper-case letter are significantly
different by Duncan's mean separation (
p
< 0.05)
5°C 10°C 20°C
Ripe 83 ± 5.2aXY 96 ± 4.2aX 74 ± 5.2bY
Partially ripe 84 ± 3.6aX 79 ± 3.1bX 76 ± 5.5bX
Unripe 53 ± 6.4bY 83 ± 4.4bX 92 ± 4.4aX
CAUTION: There are at least three errors in this table. Can you find them? Answers are at the end
of the chapter
Answers to Questions Raised in Fig.
8.1
Both are representations of the same data. The top plot is the change of weight by
the author during 15 weeks on the Sonoma Diet (Gutterson,
2011
) . The bottom plot
records weight loss during the same 15 weeks. The bottom plot looks more dramatic
because the data are displayed over a narrower range of numbers. When displaying
data, we should be sure not to fool our readers or ourselves!
Answers to Questions Raised in Table
8.3
Errors include (1) the mean separation test was performed both down and across—
unless the SS are partitioned, this is not a meaningful test, (2) Duncan's multiple
range test is not valid for continuous variables like temperature—if the means are to
be separated across by temperature, either use mean separation tests like LSD or
perform regression analysis, and (3) the phrasing of the mean separation lettering is
incorrect as it indicates that the value followed by XY is significantly different than
the values followed by X and by Y. Also, we do not know whether the letters a & b
or X & Y are designating differences down or across. In addition, some reviewers
do not like to see the reporting of both the standard deviation and a means separa-
tion. Other reviewers like to see both statistics.
References
Gutterson C (2011) The new Sonoma diet: trimmer waist, more energy in just 10 days. Sterling
Publishing, New York
Mason RL, Gunst RF, Hess JL (2003) Statistical design and analysis of experiments, with applica-
tions to engineering and science. Wiley, Hoboken
Ott RL, Longnecker MT (2008) An introduction to statistical methods and data analysis. Duxbury
Press, Paci fi c Grove
