This document discusses scientific concepts like the scientific method, experimental variables, controls, and eliminating bias. It provides explanations and examples of key terms: - The scientific method involves observation, hypothesis, experiment, and conclusion. Variables are things that change during experiments while controls remain the same. - Scientific laws describe observable phenomena through statements or math. Theories explain how natural events work based on testable hypotheses. Facts are objective observations. - Experiments require identifying independent and dependent variables and controlling other factors to make tests fair. Blind and double blind studies aim to reduce researcher bias. - Objective data involves measurement while subjective data includes opinions. Graphs show relationships between variables. The scientific method seeks to eliminate bias through

1. Data Analysis & Interpretation
Experiment Design: Eliminating Variables & Bias
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Science is Organized Knowledge

2. Review Quiz
In your lab notebook, please answer as best you can:
1. What is the scientific method (definition)?
2. Name the four basic steps of the scientific method.
3. What is an experimental variable?
4. What is an experimental control?
5. What should you do before forming a hypothesis?
(Three parts of the “Observation” step.)
Bonus Question: What is the difference between a scientific fact and a
scientific observation?

3. Review Quiz
In your lab notebook, please answer as best you can:
1. What is the scientific method (definition)?
• A step-by-step method for solving problems.
2. Name the four basic steps of the scientific method.
• Observation, Hypothesis, Experiment, Conclusion
3. What is an experimental variable?
• Something which changes during the course of the experiment.
4. What is an experimental control?
• The parts of an experiment which do not change to which all other results
can be compared.
4. What should you do before forming a hypothesis?
(Three parts of the “Observation” step.)
• Form a question (problem/objective/curiosity), make observations or
think about what you already know, and research the topic.
Bonus Question: There is NO difference between a scientific fact and observation!

4. Fact - Theory - Law
F = ma
• Fact:
– an objective, verifiable observation of something
that occurs in our natural world
– i.e. heat exchange, movement, gravity's effect,
natural selection, etc.
• Theory:
– an explanation of how natural occurrences work
• it can be observed, repeated, and tested with predictable results
• a hypothesis that is proven correct often explains part of a theory
– i.e. Theory of Gravity, Theory of Evolution, Kinetic Theory of Matter
• Law:
– a verbal or mathematical description of observable phenomenon
– i.e. Newton's Second Law of Motion:
• or Newton's Third Law of Motion: "For every action, there is an equal and
opposite reaction."

5. Scientific Law
• Definition: A law in science is a generalized rule to
explain a body of observations in the form of a verbal
or mathematical statement.
– Scientific laws imply a cause and effect between the
observed elements and must always apply under the same
conditions.
– Scientific laws do not try to explain 'why' the observed
event happens, but only that the event actually occurs the
same way over and over.

6. "A Fair Test" Experiment
Who is the Fastest?

7. Experimental Variables
• Independent (manipulated) Variable: the things we
change to see what effect it has on our results
• Dependent (responding) Variable: the different
outcomes or results/data of the experiment that
change depending on the independent variable
• Controlled Variables: things that may affect the
outcome and make it an unfair test
Independent Variable
– Runner
– BP: water
Dependent Variable
– Time
– BP: plant health
Controlled Variables
– Distance,
weight, start
– BP: soil, pots,
sunlight

8. Experimental Controls
• Controlled Variables: things that might affect the outcome
and make it an unfair test.
• Control Group: the group that is studied with no
change in the independent variable
– example: when a new drug is studied, some subjects do
not receive the medicine so that the new drugs effect can
be compared to something
• Researcher Bias: preconceived ideas that affect how
data is collected
– Scientists always try to fit their data into a framework that
makes sense with their personal beliefs (worldview).

9. Data Collection
• Subjective data
– Results that involve an opinion or individual judgment to
record data
• examples:
– which flower is the prettiest
– which plant looks the healthiest
– how good does the food taste
• Objective data
– Results that require measurement to record data
• harder for researcher bias to affect
• examples:
– which flower has the largest petals
– which plant has the tallest stem (or greatest number of leaves)
– how much of the food was eaten

10. Controlling Bias
• Blind Studies: research subjects do not know if
they are in the control group or the test group,
researchers know who is in which group.
• Double Blind Studies:
neither subjects nor scientists
know who is in the control
group or the test group until
all data has been collected.

11. Bias in Scientific Research
• Hypothesizing requires speculation
– bias is an assumed belief that affect the way you see and
understand things
– bias is always present when formulating a hypothesis
• The Scientific Method forces only the
facts to be considered
– seeks to eliminate variables that can skew
results
– encourages collaboration & accountability
• shared results, repeated studies
– still, bias is ALWAYS present & affects
many research outcomes

12. Interpreting Data
• Graphs are often
used to show the
relationship
between the
independent
variable and the
outcome.
1. exercise/hair loss
2. income/SAT
3. driving practice/
accidents
4. sugar/sleep
1. 2.
3. 4.

13. Experiments 3.2, 3.3, & 3.4
Surface Tension Demo