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 is specific 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 happened to the seventh chicken?

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 took a random group of 10 children together and then gave them all chocolate cake. If you observed what happened, you may never know if your observations were due to the chocolate cake or if it was due to some other factor (e.g., the particular children you chose, the weather, their mood, etc.).

One way around this problem is to create two groups that are identical in every way except for one; that one difference is the variable that you manipulate. If you were to use the above example, you could take the 10 random children and group them into two sets of five children (Groups A and B). You would try to have the same number of girls as boys, as well as grouping together similar weights and heights to end up with two groups that look fairly identical to one another.

Group A would get chocolate cake becoming your experimental group.

Group B will not get any chocolate cake. Therefore, it is called the control 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.

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 1) variable, 2) the control group, and 3) 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: Develop 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 developed your two hypotheses 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

If you don’t know how to make tables in Microsoft Word, you also may list people and their results manually (i.e. Harold 28 cm; 84 beats/min). You also might try using the Help feature in Microsoft Word to help you create a table or do a quick search of the internet.