The Scientific Method

What is the Scientific Method? A logical problem solving process to investigate a scientific problem. No one completely correct set of steps Depends on problem/research

Steps in the Scientific Method State the Problem Research Form a Hypothesis Design an Experiment Test the Hypothesis Organize the Data Draw Conclusions

State the Problem Observe a discrepancy Doesn’t belong Unexpected Example: My snow peas aren’t producing many pods.

State the Problem State the problem as a question Can’t be answered by Yes or No. Use: How, When, What, Where, and Why (Why can be problematic) Specific but not cumbersome Must be testable Two variables Independent Dependent Example: Will fertilizer increase snow pea pod production? Example: What effect does fertilizer have on snow peas?

Writing a Statement of the Problem What is the effect of chemicals? What is the effect of chemicals on health? What is the effect of vitamins on health? What is the effect of Vitamin C on health? What is the effect of Vitamin C on human health? What is the effect of Vitamin C on the occurrence of the common cold in humans?

Research Find prior information about your problem (background information) Make initial observations Use your five senses Apply previous knowledge Make inferences Gather factual information Use books, journals, computer, etc

Form a Hypothesis Predict what will happen Best guess or possible explanation Determines a possible solution Write as “If…then” or ‘If…then…than’ statement (If = cause; Then = effect) Must be testable Includes two variables Independent Dependent

Independent Variables The variable that is different or being tested. Also called the Manipulated Variable ‘Cause’ part of Cause and Effect Graphed on the X axis Example: IF fertilizer is used, THEN the plants will produce more pea pods THAN the plants without the fertilizer.

Dependent Variables The variable that responds to changes in the Independent Variable Also called the Responding Variable ‘Effect’ part of Cause and Effect Graphed on the Y axis Example: IF fertilizer is used, THEN the plants will produce more pea pods THAN the plants without the fertilizer.

Independent Variable # pea pods Dependent Variable Treatment Fig. 1. Pea Plant pod production on pea plants with and without fertilizer.

Form a Hypothesis - Examples Problem 1: What effect does fertilizer have on snow peas? Hypothesis 1: IF fertilizer is used, THEN the plants will produce more pea pods THAN the plants without the fertilizer. Problem 2: What is the effect of Vitamin C on the occurrence of the common cold in humans? Hypothesis 2: IF 500mg of Vitamin C is given daily, THEN it will prevent the common cold in humans.

Design an Experiment Establish at least two test groups Experimental-the independent variable is applied to this group Control-comparison or normal group; no independent variable applied Provide a list of materials Develop a procedure Explains what is to be done and when

Test Groups Pea Plants Control group: Test or Experimental Group: Vitamin C Water Fertilizer Placebo (no vit. C) 500 mg Vitamin C daily

Controlled Variables (Constants) Factors that remain the same throughout the experiment Are the same for both the control and experimental groups. Don’t change Includes everything except the independent variable Pea Plants: water, light, temperature, etc Vitamin C: age, sex, weight, diet, etc

Test the Hypothesis Make sure all variables are controlled except for your independent variable Follow the procedure Record your observations Record any mistakes, accidents, weather, etc. that might affect the results The experiment provides evidence for or against the hypothesis

Collect Data Use logs, journals, tables and graphs Record all observations Include things you don’t think are important Qualitative Data Quantitative Data Include time, units, duration, # trials or sets, etc. Be specific!

Organize the Data Daily Log Tables Graphs Repetitive data Continuous data Discontinuous data

Daily Log The Effect of Fertilizer on Pea Production – Daily Log Day Date Time Temp Comments and Observations 1 5/14 9 am 99 Planted seed and placed in direct sunlight for 6 hours 2-10 23 Avg. 98 Sprouts are showing in both groups 11 24 96 No discernable difference between groups 12 25 95 Same 13 26 91 Same growth rate; approx. 6 in tall. 14 27 Plants are growing full sized leaves

Tables Repetitive data Like elements read down Title goes at the TOP! Compact and easy to read Title goes at the TOP! Table 1: How to correctly set up a table. Heading Related data

Tables Fertilizer Water Group 1 18 10 Group 2 21 8 Group 3 15 11 Title Table 1: The number of pea pods produced for each treatment per group of pea plants. Fertilizer Water Group 1 18 10 Group 2 21 8 Group 3 15 11 Group 4 12 Total 66 39 Average 16.5 9.75

Graphs or Figures Visual representation Shows relationships Title at the BOTTOM! Includes: Pictures (Figures) Bar graphs Discontinuous data Line graphs Continuous data Pie charts

Discontinuous Data Sharp, dramatic differences Either – Or, no blending Examples: color Grade sex

Graphs or Figures Discontinuous Data # pea pods Dependent Variable Treatment Independent Variable Title Fig. 1. Pea Plant pod production on pea plants with and without fertilizer.

Continuous Data Regular, gradual changes Shows linear relationships Examples: Distance Temperature Time Weight Height Age

Graphs or Figures- Continuous Data Revolutions Dependent Variable Time (Min.) Independent Variable Title Fig. 1. Revolutions of an exercise wheel powered by a hamster over time.

Draw Conclusions Analyze your data and summarize your findings. Is a judgment based on the results Can agree, disagree, or reveal nothing about the hypothesis State potential flaws

Publish and/or Repeat Publish in a peer-reviewed journal Allows others to critique and test Important research: Design different experiments to test the hypothesis or generate additional hypotheses.