Hypotheses and The Scientific Method
The Scientific Method
When
scientists approach a question or a problem, they do it in a very
simple and structured way. Therefore, when we try to answer questions in
science, we give answers that we and other people can examine and
either accept or reject, based on facts.
The basic process is simple:
Observe > Hypothesize > Test Hypotheses > Draw Conclusions > Repeat
This
process gets repeated again and again. It's never over. In fact, lots
of things that we think of as facts are simply just conclusions, and
science is always working to make sure that they're as accurate and
precise as possible. Any "truth" could be revised, if new evidence
develops. This is the scientific method.
Hypotheses
So what, then, is a "hypothesis"?
Most
of us have a good sense of what this is, based on our years of
schooling. But there are a few key points to remember about hypotheses:
- A hypothesis is an educated guess, based on facts. It's not just a guess. It must be based on some evidence, even if that evidence is simply your own prior experience.
- A good hypothesis has two critical characteristics: it isspecific and it is testable. A badly worded hypothesis is pretty useless, but a well-worded one is easy to investigate.For example, if you lost your pen, a bad hypothesis might be "aliens stole it," because this is not at all testable and is not very specific either. A better hypothesis might be "I dropped it underneath my chair," because this is quite simple to test and is very specific.
Assignment Question 1: Read the scenario below and then analyze what is wrong with the hypothesis given.
Renee
has noticed that a few of her friends have better eyesight than she
does. She watches what they eat and then decides to come up with a
hypothesis. Her hypothesis is as follows: My friends who eat tasty food for lunch have the best eyesight.
Assignment Question 2: Read the scenario below and then write three of your own good hypotheses about what is going on. Be sure to keep in mind the two characteristics of a good hypothesis discussed above.
There are seven chickens in the farmyard. One morning, when you go out to feed them, you see only six. What might be occurring?
Controls
Very often, it is easier to figure out the effect something has if you have something to compare it to.
As
an example, if you were trying to determine what happens when you give
chocolate cake to children, you might run into some trouble if you got a
group of 10 kids together and then gave them all chocolate cake. If you
observed what happened, you might never know if what you noticed was
due to the chocolate cake or if it was due to some other factor (the
particular kids you chose, the weather, their mood, your personality,
etc.).
One way around this problem is to create two groups that are identical in every way except for one; that one difference is thevariable that
you manipulate. If you were to use the above example, you could take
the 10 random children and group them into 2 sets of 5 kids (call the 2
groups A and B), being careful to make sure that there were about as
many girls as boys, chubby and skinny kids, and tall and short kids.
That way, you end up with 2 groups that look pretty identical to one
another.
So if you took Group A and gave them the chocolate cake, this becomes your experimental group.
Group B will get no chocolate cake at all. Therefore, it is called thecontrol group,
since it is your comparison group. It is the group that receives no
experimental treatment. Sometimes, people refer to the control group as
the "normal" group, because it is supposed to represent a natural
situation.
So now when you compare Group A (experimental group) and Group B (control group), you can make some meaningful comments about what effects the chocolate cake (the variable) had.
Assignment Question 3: Read the story below and identify the variable, the control group, and the experimental group.
Crunch
Inc. has decided to test out some new, no-salt potato chips. It hires
300 people and splits them into two groups that are mostly identical
with regard to age, weight, height, gender, etc. The first group eats 2
ounces of regular potato chips and then completes a survey. The second
group eats 2 ounces of the new, no-salt potato chips and completes the
same survey.
Applying the Scientific Method to Your Body
Now that you know a bit about the scientific method and hypotheses, examine this list of measurable body characteristics:
| Pulse Rate (beats per minute) | Seated Breathing Rate (breaths per minute) |
| Age (years) | Height (inches or centimeters) |
| Foot Size (inches from big toe tip to heel) | Hand Size (distance from tip of middle finger to base of palm) |
| Width of Mouth (inches or centimeters) | Body Weight (pounds or kilograms) |
Assignment Question 4: First, come up with a good hypothesis about how any two of these 10 characteristics might be related to one another. It
doesn't matter if they really are related or not, what matters is that
you use what you know about hypotheses to come up with a good one. Here is an example (do not use this hypothesis in your answer): "As
a person's shoe size increases, his/her pulse rate decreases." or "The
higher a person's shoe size, the slower his/her pulse rate."
Assignment Question 5: After
you have your own hypothesis on how two of the characteristics relate
to each other, take measurements from people you know. You'll need to
collect data from at least five real
people. You also can count yourself in the sample. Be sure to include
the person's name next to the person's data, and put it into a table in
your lab assignment. The table might look something like this:
| person | foot size | pulse rate |
| [Your name] | ||
| Harold | 28 cm | 84 beats/min |
| Gena | 20 cm | 91 beats/min |
| Rita | 18 cm | 98 beats/min |
| Jerry | 21 cm | 107 beats/min |
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