Chapter 1, Concept 1.3, The Scientific Method
Overview
I. Making Observations
II.
Form & Testing Hypothesis
III.
Experimental Controls & Repeatability
IV.
Theories in Science
V. What Is Outside Science
Objectives
1.
Know the steps in applying the scientific
method and be able to identify them in a novel
situation.
2.
Be able to use the scientific method to design
an experiment.
3.
Be able to identify what is "inside" and outside
science.
Lecture
The Scientific Method
The scientific method is a way of collecting
data and analyzing it to determine if it answers
a question.
Previous to the scientific method being developed,
people used various methods of answering their
questions, with varying levels of success.
The scientific method has been the basis of
our current, 1st world technology.
Personally, I'm glad for indoor plumbing and
lights anytime I want them.
In this course, we will be using a form of
the scientific method that is based on proposing
and testing hypotheses.
Making Observations
Scientific research generally begins with
an observation.
I'm going to use a different example than
the one in the textbook.
This summer, as I was putting away the mower
after mowing the lawn, I felt a stabbing,
burning pain on my leg.
It was a very visceral observation.
Here's a picture of the site.
This is designed to generate to sympathy.
Actually, I took a picture of the bite to
use in my microbiology course to illustrate
inflammation, but it works well here.
Closely followed by the observation is the
question -- what stung me?
The observation and question tend to occur
so closely that we have a hard time separating
them, but it is good to make sure you understand
the difference between an observation and
a question.
Also notice that I made the assumption that
I was stung.
It could have been a bite, a stab, or the
first sign of some strange new skin disease,
but we will stick with my initial question
that a 'bug' of some sort got me.
Forming & Testing Hypothesis
So, I made a tentative answer to my question,
or, in scientific terms, I made a hypothesis.
But first, I had to draw on previous observations.
Assuming I had been stung or bit, there were
three prime suspects: honey bees, which I
had seen visiting the clover blossoms in the
lawn while I was mowing; spiders, of which
I'd seen evidence of in the form of several
webs along the lawn -- fence boarder while
I was mowing; and yellow-jackets, of which
I'd seen several hovering around my car port
over the past several days.
Since I keep the mower in the car port, I
hypothesized that a yellow-jacket had stung
me, since I'd seen them closest to where I'd
been stung or bit.
I tested my hypothesis by first looking under
my pant leg (I did that immediately upon feeling
the pain, without consciously formulating
a hypothesis).
There was nothing there, which seemed to support
my hypothesis that the cause of the pain was
a flying insect.
Next, I looked around the underside of the
car port roof, searching for a wasp's nest.
I didn't see any.
I also didn't see any webs (which was odd)
or unusual concentration of bees.
My test tended to falsify my hypothesis.
I limped into the house and the whatever-it-was
went away in a three days.
Experimental Controls & Repeatability
In science, we try to have controls.
Controls are the same experiment but without
the variable we are testing.
So, a control for my experiment, if I were
to do such a thing, would be to obtain a honey
bee, a spider, and yellow-jacket from my yard
and allow each to sting or bite my leg.
I because I had seen it happen, I would know
what caused the welts, they would be the controls.
I could then compare the results with the
unknown bite.
Not being that dedicated to science, I was
willing to stop the experiment and I didn't
perform these controls.
Experiments should be repeatable.
In the lab and in the field, we run the experiment
more than once.
If it we get the same results for all or most
of the experiments, the data support each
other.
If we get the results only once, it is considered
a fluke.
Unfortunately, I repeated my experiment.
The next time I mowed the lawn, I felt the
same pain again.
Again, nothing up my pant leg.
Disgusted, I limped into the house to find
some sort of remedy.
But, first, I knelt on my couch to plug in
a fan and feel the same pain.
This time, a yellow-jacket flew out, which
supported my initial hypothesis.
After doctoring my stings, I went back outside
and found the hive.
It was on the edge of my gravel driveway,
where I mow the weeds at the very end of my
mowing pattern.
I'd been mowing over the hive, so I consider
the stings to be justifiable self-defense
on the part of the yellow-jackets.
I was going to leave the hive alone.
Yellow-jackets eat other insects and my yard
is lousy with box elder bugs, but, the stings
turned into this horribly painful and itchy
inflammation over most of my legs by 24 hours.
The black marks were put there by the urgent
care doctor so we could test the hypothesis
that the inflammation wouldn't continue to
spread after I started taking the medication
he prescribed.
Based on the observation that there was more
inflammation with the 2nd and 3rd stings,
I made the hypothesis that I'm allergic to
yellow-jacket venom.
Not wanting to test that hypothesis, I sprayed
the hive the next chance I got.
Theories in Science
Enough about the great yellow-jackets stings.
We covered what a theory is during the evolution
lecture, but let's briefly review.
A theory is supported by data.
In other words, it started out as a hypothesis
and it has been supported by a lot of experiments.
A theory had predictive value.
It can be used to develop more hypotheses.
It can be used to predict what fossils we
will find eventually.
We continue to use theories until there is
data to falsify it.
When that happens, we come up with a new theory
that is supported by all of the data and has
predictive value.
What Is Outside Science
Not everything can be tested by the scientific
method.
The hypothesis must be testable and falsifiable.
That is something to keep in mind when you
are designing your hypothesis in lab and when
answering questions on exams.
Reminder
You should be able to:
Know the steps in applying the scientific
method and be able to identify them in a novel
situation.
Be able to use the scientific method to design
an experiment.
Be able to identify what is "inside" and outside
science.
