Adhering to the proper assumptions
in any statistical analysis is very important. And there seems to
be an assumption for everything. For this post, I’d like to
clear up some confusion about one particular assumption for
A data set is normally distributed
when the data itself follows a uni-modal bell-shaped curve that is
symmetric about its mean. This graph, created from the... Continue Reading
We humans do have a tendency to succumb to
gold rush fever.
And this can happen even in the left-brained, rational field of
After we collect our data, it’s difficult to resist the urge to
desperately dash for
p-values, as if they were 70% off at Macy’s the day after
Thanksgiving.But no matter how well-versed you are in statistics, it’s good
practice to get into the habit of intuitively... Continue Reading
In an earlier post, I focused
on using Minitab to present the coupon data I collected from my
e-mail inbox into a bar chart. The bar chart made it easy for me to
visually analyze which days of the week are better or worse for
receiving the best coupons from my favorite retailers. As a
reminder, here’s how I ranked each coupon’s worthiness:
worth your timeOffering average
savings (A “noteworthy”... Continue Reading
It’s summer and maybe you’re traveling to Florida’s coast for a
beach vacation (or just wishing you were, like I am)! I got the
chance to talk to Dr. Henry Briceño from the Southeast
Environmental Research Center (SERC) about how he and his team use
statistics to monitor Florida’s water quality.
The center’s research projects throughout South Florida have
provided a basis for management decisions... Continue Reading
Sometimes, statistical terms can seem like they were zapped down
from outer space by sadistic, mealy-mouthed aliens: R-squared
adjusted, heteroeskadasticity, 3-parameter Weibull
But not all statistics terminology
should leave you feeling woozy and glassy-eyed. Some terms
actually make intuitive sense. Knowing those terms can help
you get a handle on output that may seem fuzzy at... Continue Reading
Data collection involves taking measurements, and this seems
like a simple thing when the subject is relatively simple.
However, even the simplest of cases has the potential to be messed
up. I found this out the hard way once. I hope sharing it
helps you avoid a similar experience.
Experienced researchers and quality practitioners know they need
to verify that a measurement system provides valid... Continue Reading
We use statistics because it's usually not practical to collect
all of the data from an entire population. Instead, we sample the
population, and then use statistics for that random sample to draw
conclusions about the whole population.Many common statistical procedures require data to be approximately
normal -- in other words, to roughly follow the bell curve.
But what happens when you have a... Continue Reading
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