Download The Scientific Method: Tongue Twisters

The Scientific Method: What’s Your Sign?
The scientific method is the process that allows scientists to find answers to the questions they
ask. All reputable scientific inquiry around the world is conducted using the scientific method.
In order to have confidence in the discoveries that modern science reveals to us, a well-informed
citizen needs to learn to use and understand the scientific method.
Objectives
When you have finished this lab, you should be able to:
1. demonstrate the ability to use the scientific method, including
observation, hypothesis formation, experimental design, analysis, and
conclusion formation.
Introduction:
The following is a brief explanation of how the scientific method is conducted:
1. Observe: Make observations. Here are a few I’ve made:
a. Many people believe in astrology.
b. Many great leaders have similar personality traits.
2. Question: Based on your observations pose a question which can be answered with a yes
or no. An example might be “Do people who are born under the same zodiac sign have
similar traits and fates?”
3. Hypothesis: Formulate a possible answer to the question. This is known as an
hypothesis. Ours might be “Presidents of the United States will be born under one (or
only a few) astrological signs.” Notice that several other alternative hypotheses might
Spring 2006
1
also answer this question. Can you give one? You may choose to test any of these
hypotheses.
4. Prediction: Using your question and hypothesis create a prediction that follows this
recipe: “If . . . then . . .” If astrology has a basis in fact, then people possessing the
leadership qualities essential to becoming President of the United States will be grouped
under one or a few zodiac signs.
5. Experiment: Design an experiment to test your hypothesis or to determine if your
prediction is correct. Your experiment must be designed so that the results will either
support or reject your hypothesis. How large of a sample size do you need to make the
experiment believable? (Each time you repeat your experiment and get similar results
you will strengthen the confidence others will have in your results.) Your experiment
should also be able to be performed by other investigators producing similar results.
6. Analysis and Conclusion Formation: Raw data is usually analyzed by organizing it
into a more manageable form. Statistical analysis is performed. Data can be organized
into tables and figures to allow investigators to see trends.
Background information on astrology.
Are our lives influenced and/or affected by the signs of the zodiac? Is what we are to become
in life determined by the zodiac sign under which we were born? If that is so, then isn’t it
reasonable that a group of people all pursuing the same career, were more likely to be born under
one or a few of the zodiac signs? Or is it the case that the birth dates of these people are
randomly distributed among the signs of the zodiac? Let us apply the scientific method to his
problem.
The zodiac consists of 12 divisions or signs. Astrologers--individuals who tell fortunes by
studying the stars--believe that a person comes under the influence of the sign under which he or
she was born. We will use the scientific method to investigate the possibility of such
contentions.
Our hypotheses (called the null hypothesis, Ho) explains what would be expected if zodiac
signs have no influence on our lives. If we prove the null hypothesis, we must have one or more
alternative hypotheses, H1, ready to accept.
What is our null hypothesis?_______________________________________________________
What is our alternative hypothesis?_________________________________________________
Spring 2006
2
We will need to collect birth information from the group we wish to study. The signs and
dates of the zodiac are generally accepted as follows.
If your birth date is between . . .
January 20 through February 18
February 19 through March 20
March 21 through April 19
April 20 through May 20
May 221 through June 20
June 21 through July 22
July 23 through August 22
August 23 through September 22
September 23 through October 22
October 23 through November 21
November 22 through December 21
December 22 through January 19
. . . then your sign is . . .
Aquarius
Pisces
Aries
Taurus
Gemini
Cancer
Leo
Virgo
Libra
Scorpio
Sagittarius
Capricorn
Collect your raw data in the “Observed” column of the table below.
Zodiac Sign
Aquarius
Observed #
Expected #
(O-E)
(O-E)2/E
Pisces
Aries
Taurus
Gemini
Cancer
Leo
Virgo
Libra
Scorpio
Sagittarius
Capricorn
Total
Spring 2006
3
With this raw data, we are ready to test the null hypothesis. Data of this type can best be
tested using the “Chi-squared Goodness of Fit” statistical procedure. In other words, we wonder
how “good” our data fits our prediction.
Here is a brief example of this analysis:
Group
A
B
C
D
E
Totals
Observed #
30
50
20
40
60
200
Expected #
40
40
40
40
40
200
(O-E)
-10
10
-20
0
20
0
(O-E)2/E
2.5
2.5
10.0
0
10.0
X2 =25.0
We will reject our null hypothesis if the Chi-squared (X2) value is too big. How do we know
it is too big? As this isn’t a statistics class, we’ll skip the derivation and just say that for our brief
example, we will reject the null hypothesis if X2 is greater than or equal to 9.49. (This value is
taken from a Chi-squared values table, α=0.05, df=4).
For the presidential birthday/astrology example we have 12 classes, the signs of the zodiac, and
the critical value is 19.68. (This value is taken from a Chi-squared values table, α=0.05, df=11).
Written Assignment:
You may test any hypothesis you wish. You will write up this experiment in formal scientific
style. Consult the handout, “How to Write a Scientific Paper” as needed. This is due at your
next lab session.
Spring 2006
4
How to Write a Scientific Paper
We will write up the results of our experiment as a lab report. This report could be submitted
to a journal for publication and scrutiny by the scientific community. The journal will send the
report out to prominent scientists in that field of study for review. If the experiment is well
designed and conducted and the report is well written, the reviewers will approve the report. The
journal will then accept the report for publication. By following this process the results of
experiments are made public so that other scientists can benefit from the new information.
The following are the major parts to a lab report and a brief description of each part.
TITLE: The title should give the reader a concise idea of the topic of your experiment.
INTRODUCTION: This is where you introduce your topic by defining and clearly stating what
your question, hypothesis, and predictions are, and giving any important background
information.
MATERIALS AND METHODS: In this section you explain exactly how you conducted your
experiment and what materials you used. This section is not a ‘recipe’ and should not list a
series of steps, but rather should consist of text in paragraph form.
RESULTS: Here you report the results of your experiment (the data) in a descriptive text.
Tables and/or figures are often presented here to illustrate what is being said in the text.
DISCUSSION: Here you explain what your results mean and how your results relate to the
original question, hypothesis, and predictions. It is important to tell the reader if the
experimental results support or reject your hypothesis. You NEVER prove your hypothesis!
(This is so important that I will deduct one point every time the word ‘prove’ is used). If you
reject your hypothesis tell the reader why...was the hypothesis a bad one or was the experiment
poorly designed or conducted? (But don’t fall into the common error of making excuses for
shoddy work!) What would you change about your hypothesis or experiment so it would work
better next time? Whether or not you supported your hypothesis every investigator should
explain what additional questions the experiment suggests. (Usually an experiment will answer
your original question but will cause you to think of numerous other related questions.)
A lab report must follow the above format, be well organized, well written, typed, and free of
spelling and grammatical errors.
This exercise was modified from one written by Karen Townsend of the University of Scranton.
Spring 2006
5
Lab Report Rubric
(How this assignment will be graded)



Title: logical, relevant
Aim: shows what you wish to accomplish
Hypothesis: shows what is believed to be the rule





Describe what you did and what special techniques/equipment
were needed
Clear logical sequence but written in paragraph form
Easy to follow
Use active voice
Clear scientific diagrams if required to describe equipment
Results




Clear record of data
Appropriately formatted figures (graphs)
Tables where appropriate
Graphs and tables clearly marked
15
Discussion







Use the data gathered
Suggest possible explanation in terms of the hypothesis and aim
Introduce and reference relevant outside information
Identify errors, problems
Show equations needed/relevant
Show what was learned and or accomplished
Connect the discussion and the aim
5
Works Cited

Using standard format, give credit to any literature used.
7.5
7.5
10
Title Page
and
Introduction
Method
5
Language
50
Total
Make sure the report is clear, uses correct spelling, and meets scientific
literacy standards as well as double spaced, type written, 12 point New
Times Roman font, one inch margins, and page numbers.
This paper is worth 50 points. A normal day of lab is worth 10 points. Please make sure you do
a good job on this paper. No late papers will be accepted.
Spring 2006
6