powerpoint presentation - science 1101

Science 1101Science 1101

Science, Society, and the Environment IScience, Society, and the Environment I

Instructor Valerie KingInstructor Valerie King

Lecture 1 Outline

I. What is Science? A. Forms of Scientific Inquiry B. Types of Logic

II. Scientific DesignA. Scientific MethodB. Theory and Laws

III. Scientific Method in ActionA. ExamplesB. Statistics

What is Science?

“Science” derived from Latin ‘to know’Way of asking and answering questionsSeeking answers to questions about

natural phenomena (we are therefore limited to what kinds of questions we ask)

Scientific thinking reduces emotional reactions

Forms of Scientific Inquiry

Discovery or Descriptive Science– Observation– Qualitative vs. Quantitative data

Types of Logic

Inductive Reasoning– Derive generalizations based on specific

observations

Types of Logic

Inductive Reasoning– Derive generalizations based on specific

observationsDeductive Reasoning

- Specific predictions follow from general premise

Forms of Scientific Inquiry

Discovery or Descriptive Science– Observation– Qualitative vs. Quantitative data

Hypothesis-Based Science

Scientific Design

Scientific knowledge begins with an observation and a proposed explanation.

Explanation called a hypothesisA hypothesis is testable and falsifiable In science hypotheses are tested by using

them to make predictions about how a particular system will behave

Example

Hypothesis: all objects fall when dropped– Test this by dropping objects– Each object we drop is a test of our

prediction, the more successful tests the more confidence in our hypothesis

What if we drop a helium balloon?What if we drop something in the

space shuttle in space?These are clear exceptions to our

original hypothesis-does this make our hypothesis invalid?

Theories and Natural LawsTheory: a description of the world that

covers a relatively large number of phenomena and has met many observational and experimental tests

Law of Nature: theory (or group of theories) that has been tested extensively and seems to apply everywhere in the universe-they become part of the conceptual framework of a particular field

Scientific Method in Action

We use the scientific method in everyday life

Example: You got in your car to drive up here and turned the key but the car wouldn’t start (observation)


Example:You got in your car to drive up here and turned the key but the car wouldn’t start (observation)

Hypothesis: There is something wrong with the car


Example:You got in your car to drive up here and turned the key but the car wouldn’t start (observation)

Hypothesis: There is something wrong with the car

Predictions: battery dead, ignition problem, out of gas


Test predictions: turn on headlights, check spark plug wires, dip stick in gas tank



Analyze results: headlights work, strong ignition spark, no gas on dip stick-gas gauge reads half full



Analyze results: headlights work, strong ignition spark, no gas on dip stick-gas gauge reads half full

Draw conclusion: gauge inaccurate, out of gas


I want to market a new flea collar for dogs that is a natural remedy-no harsh chemicals. But first I have to see if it really works.

Hypothesis: King’s collar repels fleasPrediction: dogs wearing the King collar

will have fewer fleas than dogs not wearing the King collar

Important terms:Independent (manipulated) variable:

condition or event under study (choose 1) Dependent (responding) variable:

condition that could change under the influence of the independent variable (measure this)

Controlled variables: conditions which could effect the outcome of the expt so they must be held constant between groups.

experimental group: group(s) subjected to the independent variable

control group: group not subjected to the independent variable, used as measuring stick

reproducibility: producing the same result consistently to verify result. It is therefore important to describe your experimental design in enough detail for others to perform the same experiment.

Let’s recap

Hyp: King’s collar repels fleasPred: dogs wearing King’s collar will have

fewer fleas than those without collarIV: King’s collar DV: presence of fleasCV’s: anything that might effect the number

of fleas on the dogsCan we think of some???

Experimental Design• Obtain 500 dogs of various breeds from

local shelters. Have vet weed out the 200 dogs with the most fleas. Randomly assign individuals to 2 groups.

• Board the dogs in identical environments and treat them the same except that one group gets to wear the King collar and the other group does not

• After 2 wks. The dogs are examined by a vet for fleas.

Results: the dogs wearing the King collars were virtually free of fleas after the 2 wk period compared to the dogs without the collars which had about the same number of fleas as when the experiment began

Second Example Observation: polar bears are white, you

wonder why this is so Hypotheses:

Match arctic landscape for protection/predation White fur may reduce heat loss in warm-blooded

animals Maybe polar bears are unable to produce melanin

therefore they are white as result

• Prediction: polar bears which are white will capture more prey than those which are dark–IV: color of bears–DV: number of prey

• Experimental Design: spray paint 5 polar bears dark(experimental Group)/leave 5 white(control group) Track prey capture for 8 weeks

Effect of Polar Bear coat color on prey capture

Color of Bear White DarkNumber of Prey 12 7

Probability and Statistics

Probability: an attempt to measure and predict the likelihood of an event

Statistics: allow you to evaluate comparisons between experimental and control groups

Effect of Polar Bear coat color on prey capture

Color of Bear White DarkMean Number of Prey captured

12 7

Mean: sum the values, divide by the number of values

• Assumptions: factors thought to be true for the investigation but have not been verified or controlled– Commonly accepted information– Thought to be held constant but not controlled– Factors beyond the investigators control

because of technical or time considerations• Incorrect assumptions invalidate an

experiment!

• Assumptions:1. All of the bears are equally hungry2. Spray painting the bears has no effect on their behavior etc. accept to make them stand out on the ice3. Our sample of bears is a good representation of the polar bear population in general

Statistics

Sample Size: # of observations necessary to have a reliable representation of a population

Confidence Limits: estimates that reflect the reliability of your mean (average)– Probability your sample is similar to other

random samples of that population

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