Lab Topic 1 Science: A Way of Gathering Knowledge

The Scientific Method Scientific Method = Process which outlines a series of steps used to answer questions. The key ingredient of the scientific process is the hypothetico-deductive method, which is an approach to problem-solving that involves: 1.asking a question and formulating a tentative answer or hypothesis by inductive reasoning. 2.using deductive reasoning to make predictions from the hypothesis and then testing the validity of those predictions.

Hypothesis Educated guess proposed as a tentative answer to a specific question or problem Less used terms ◦ Null hypothesis is the hypothesis stated as a negative ◦ Alternative hypothesis is the hypothesis

Reasoning Inductive Reasoning = Making an inference from a set of specific observations to reach a general conclusion. Deductive Reasoning = Making an inference from general premises to specific consequences, which logically follow if the premises are true. ◦ Usually takes the form of If...then logic. ◦ In science, deductive reasoning usually involves predicting experimental results that are expected if the hypothesis is true.

Experimental Design Independent variable ◦ That which will be varied during the experiment. ◦ This is sometimes the “cause” of something.  Graph on X axis Dependent variable ◦ Variable that is measured, counted, or observed in response to experimental conditions. ◦ This sometimes the “effect”.  Graph on Y axis

Experimental Design Control variables ◦ Other variables that could influence the dependent variable, but which are kept constant. Level of treatment ◦ Intensity, frequency, etc., etc. Control treatment ◦ The independent variable is held at an established level or is omitted

Hypothesis: Increased levels of sulfur dioxide adversely effect plant growth Group A plants placed in filtered air environment (0% sulfur dioxide) Group B placed in 3% sulfur dioxide atmosphere Plant height is measured at 2, 4, 6, 8, and 10 weeks of exposure. What is the dependent variable? Height What is the independent variable? Time

Hypothesis: Increased levels of sulfur dioxide adversely effect plant growth Group A placed in filtered air environment (0% sulfur dioxide) Group B placed in 0.1% sulfur dioxide atmosphere Group C placed in 0.5% sulfur dioxide atmosphere Group D placed in 1.0% sulfur dioxide atmosphere Group E placed in 10.0% sulfur dioxide atmosphere Plant height is measured at 6 weeks of exposure. What is the dependent variable? Height What is the independent variable? Concentration of Sulfur Dioxide

The Experiment: You are to work as a group to conduct an experiment which will assess recovery time after exercise. You should, as a group, decide upon a factor which you believe could have an impact on cardiovascular health. That factor could be age, gender, amount of exercise, diet, etc, etc. etc. From your group you will select two individuals that vary in regards to this factor (male-female; youngest-oldest, couch potato- world class athlete, etc.). Those two people will then be your source of data during the experiment.

The Experiment As an example …I have chosen smoking. In my group I may have had a two-pack-a-day person and a never-touched-the-evil-weed person. They will carryout a standardized Step-Test to document their recovery time after exercise. Aside…It is normal for pulse and respiratory rate to climb when you engage in a physical activity…that is what is supposed to happen as your body responds to the increased needs for oxygen and circulation that the exercise state demands. When you cease exercising the pulse and respiratory rate should rapidly return to normal. If instead, they remain elevated after exercise cessation…that is bad!

Testing recovery time in smokers vs non-smokers. Question: Do smokers have poorer cardiovascular fitness than non-smokers? Null Hypothesis: Smokers do not have poorer cardiovascular fitness than do non-smokers Alternative hypothesis: Smokers do have poorer cardiovascular fitness tan do non-smokers

Experimental Design Step for 3 minutes at 30 steps per minute Pulse will be measured before procedure and will be measured at 1, 3, 5, 7 and 10 minutes after procedure. Respiratory rate will be measured before procedure and will be measured at 1, 3, 5, 7 and 10 minutes after procedure.

What are the….? Dependent variable? ◦ Pulse Rate and/or Respiratory Rate Independent variable? ◦ Time after exercise Controlled variables? ◦ Gender, age, diet, ethnicity, etc. etc. etc. Level of Treatment? ◦ Step Test 3 30steps/minute Control? ◦ Reading taken before exercise…time=0

Replication 1 Pulse Breathing Rate Replication 2 Pulse Breathing Rate Average Pulse Breathing Rate Time = 0 (control) 1 minute after exercise end 3 minute after exercise end 5 minute after exercise end 7 minute after exercise end 10 minute after exercise end Data: Pulse and breathing rates at different times after 3 minutes of exercise in a person with the following characteristics ________________