1. Introduction to Scientific Method: Observation and Data
Ms. Day/ Honors Biology
Lecture #4
9/18/2014

2. Observation: using your 5 senses to collect information
Data: scientific information
Inference: a logical conclusion or assumption based on your observations

3. DATA
2 TYPES:
Quantitative: includes observations or data that involves numbers (#’s), amounts or quantities
Qualitative: includes observations that DO NOT involve numbers; Observations or data that is descriptive.

4. Scientific Method

5. **(Initial) Observation : use your 5 senses
What are the steps?
**(Initial) Observation : use your 5 senses
1. State the problem or question:
What are you trying to solve or research?
2. Form your hypothesis:
an educated or logical prediction to answer your problem question; use your prior knowledge
Not just a “guess”
IT MUST BE TESTABLE!!!
“If…then…because” statement
Use independent, dependent variable & prior knowledge
3. Plan your experiment:
decide your procedure, control, variables & materials

6. 4. Perform your experiment: 5. Analyze your data (Results):
Collect data (both qualitative and quantitative)
5. Analyze your data (Results):
Make sense of your data
put it in LINE graphs/charts/table, etc.
6. Conclusion:
Sum up your findings (data)
Restate your hypothesis and state whether it is rejected or accepted based on your results
CITE your quantitative and/or qualitative data!!! EXPLAIN your numerical data.
State and EXPLAIN any experimental error(s) (called error analysis)

7. A Controlled Experiment
Experiment = process to collect data
There are (usually) 2 groups in an experiment:
Experimental (or test) group
Control group

8. Experimental vs. Control Groups
Experimental (Test) Group
Control Group
1 variable (thing) changes or is tested
Comparison group
No changes
“Normal” conditions

9. + Example: HOW WILL FERTILIZER AFFECT PLANT GROWTH?
WITH FERTILIZER WITHOUT FERTILIZER
(plants normally don’t have fertilizer)
>>>>ONLY CHANGE (test) 1 VARIABLE (thing): THE PRESENCE OF FERTILZER
Conditions (or variables) that NEED to remain
the same for a controlled experiment:
AMOUNT OF SUNLIGHT,
SOIL,
TYPE OF POT,
TEMPERATURE,
SPECIES OF PLANT
TEST GROUP + +
CONTROL GROUP

10. A controlled experiment will have different variables:
Constant variables
Independent variable
Dependent variable

11. Standard (constant) Variables
Things that are kept EQUAL in all treatments (groups)
Aka-control variables or constants
**NOTE: Different than CONTROL GROUP

12. Independent Variable Dependent Variable
A controlled experiment will have 2 different variables:
Independent variable (“If….then…)
Dependent variable (If…then…)
Independent Variable
Dependent Variable
The thing (variable) that you SET UP AS DIFFERENT at the beginning of the experiment.
Ask “What variable changed in the experimental group?
“WHAT ARE YOU TESTING or CHANGING?”
The MEASURED outcome in the experiment.
Ask “What is being measured/recorded?”

13. Independent Variable
What are you testing/changing?
X-axis
Dependent Variable
What are you counting/measuring?
Y-axis

14. If time is present, it is ALWAYS the x-axis (independent variable)
Y- Axis = Dependent variable

15. + + Independent variable: WHAT ARE YOU TESTING? Fertilizer
Example: HOW WILL FERTILIZER AFFECT PLANT GROWTH?
WITH FERTILIZER WITHOUT FERTILIZER
(plants normally don’t have fertilizer)
Independent variable: WHAT ARE YOU TESTING?
Fertilizer
Dependent variable: WHAT ARE YOU MEASURING?
Plant Growth
TEST GROUP + +
CONTROL GROUP

16. Now let’s practice with Spongebob…
Which people are in the control group? What is the independent variable? Patty Power Mr. Krabbs wants to make Bikini Bottoms a nicer place to live. He has created a new sauce that he thinks will reduce the production of body gas associated with eating crabby patties from the Krusty Krab. He recruits 100 customers with a history of gas problems. He has 50 of them (Group A) eat crabby patties with the new sauce. The other 50 (Group B) eat crabby patties with sauce that looks just like new sauce but is really just the old sauce with food coloring. Both groups were told that they were getting the sauce that would reduce gas production. Two hours after eating the crabby patties, 30 customers in group A reported having fewer gas problems and 8 customers in group B reported having fewer gas problems.
What is the control group?
What is the independent variable?
What is the dependent variable?
Group B
Type of Sauce
Amount of gas

17. Testing Hypotheses Not just a “guess” IT MUST BE TESTABLE!!!
“If…then…because” statement
Use independent, dependent variable & prior knowledge
Science can only test hypotheses that can be proven false
YOU CANNOT PROVE A HYPOTHESIS TO BE TRUE!!!
SCIENCE = TESTABLE; BASED ON COLLECTED EVIDENCE CALLED DATA
BELIEF = OFTEN BASED ON IDEAS OR OPINIONS NOT DATA
New techniques and knowledge have made previously unscientific hypotheses available for testing
Experiments either reject or fail to reject (often said to support) the hypothesis
Rejection leads to modification or dismissal of hypothesis

18. Theory vs. Models
Scientists test hypotheses MANY times in different ways! (i.e.- w/ new research tools, equipment, etc)
Many “types” of knowing…science-based knowledge based on careful, repeated observations/testable hypotheses.
THEORY = a well-tested explanation that is supported by A LOT of evidence (data)
Much broader than a hypothesis
MODEL = physical, mental or mathematical representations of how people understand a process or idea

19. Additional Information…
Essential to ALL experiments is:
Replication!!!
You NEED to consider your number of trials
Use the EXACT same conditions in EACH trial
Why?
To determine if the results are consistent  this INCREASES our confidence in the resulting data
BUT…
A certain amount of variation is NORMAL!
Increasing trial # allows us to obtain an AVERAGE RESULT from different trials.

20. Additional Information…
Essential to ALL experiments is:
2) Sample size
You NEED to consider your sample size when drawing conclusions
For example…
You are working with plants and decide to plant 2 control plants and 2 test plants.
1 test plant and 2 control plants die during the experiment
WHAT HAPPENS NOW? 

21. Additional Information…
Essential to ALL experiments is:
3) Clear procedure
Do NOT use pronouns!
Use “directional” language
Example:
Place ______ in _____.
Fill 20 ml of water in a 50 ml graduated cylinder
Someone MUST be able to REPEAT your procedure over and over to produce similar results!!

22. More practice with Spongebob…