Lab Topic 1Lab Topic 1Science: A Way of Gathering Knowledge

The Scientific MethodThe Scientific MethodScientific 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.

HypothesisHypothesisEducated 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

ReasoningReasoningInductive 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 DesignExperimental DesignIndependent 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 DesignExperimental DesignControl 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 Hypothesis: Increased levels of sulfur dioxide adversely effect sulfur dioxide adversely effect plant growthplant 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 Hypothesis: Increased levels of sulfur dioxide adversely effect sulfur dioxide adversely effect plant growthplant growth

Group A placed in filtered air environment (0% sulfur dioxide)

Group B placed in 0.1% sulfur dioxide atmosphereGroup C placed in 0.5% sulfur dioxide atmosphereGroup D placed in 1.0% sulfur dioxide atmosphereGroup 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: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 ExperimentThe ExperimentAs 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 Testing recovery time in smokers vs non-smokers.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 DesignExperimental DesignStep for 3 minutes at 30 steps per

minutePulse 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….?What are the….?Dependent variable?

◦Pulse Rate and/or Respiratory RateIndependent variable?

◦Time after exerciseControlled variables?

◦Gender, age, diet, ethnicity, etc. etc. etc.

Level of Treatment?◦Step Test 3 minutes @ 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 ________________