observation vs. inference

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Observation vs. Inference. Observation: the act of noting or perceiving objects or events using the senses Inference: a judgment based on reasoning from evidence known or assumed to be true. Observation or Inference?. I think there is someone at the door Inference The child is happy - PowerPoint PPT Presentation

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Page 1: Observation vs. Inference
Page 2: Observation vs. Inference
Page 3: Observation vs. Inference

Observation vs. Inference

• Observation: the act of noting or perceiving objects or events using the senses

• Inference: a judgment based on reasoning from evidence known or assumed to be true

Page 4: Observation vs. Inference

Observation or Inference?• I think there is someone at the door• Inference• The child is happy• Inference• The liquid is colorless• Observation• The dog is scratching because it has fleas• Inference• The cat is afraid of the vacuum cleaner• Inference

Page 5: Observation vs. Inference

Make an Inference• Andruw Jones has 8 luxury cars

• The ice cream in the freezer is melted

• The doors to my favorite restaurant were locked on Friday

• Jim was late to 1st period

• Traffic was worse than usual this morning

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1 2 3 4 5

6 7 89 10

11 12 13 14 15

Page 8: Observation vs. Inference

Types of Observations

• Quantitative: Involve a number or measurement

• The water has a temperature of 65º C, the nickel has a mass of 5 g, a dime is 1 mm thick, etc.• Qualitative: Observations made using the

senses• The wood smells like pine, I hear a loud

noise outside, the syrup feels sticky

Page 9: Observation vs. Inference

The Scientific Method

Page 10: Observation vs. Inference

Hydrangeas growing in my backyard

Page 11: Observation vs. Inference

Same species of hydrangea in a Michigan yard

Page 12: Observation vs. Inference

Steps in the Scientific Method

• Observe• Ask Questions, State the Problem• Form a hypothesis Hypothesis = a possible explanation

that can be tested by experimentation

• Design a controlled experiment

Page 13: Observation vs. Inference

Controlled Experiments should have:a) Independent variable – factor

manipulated by the experimenter (on x axis of graph)b) Dependent variable – factor that

responds to the independent variable

(on y axis of graph)c) Control group – used as a

standard of comparison d) Experimental group(s) – exposed

to the independent variable

Page 14: Observation vs. Inference

How would you set up an experiment to test the hydrangea hypothesis?

Page 15: Observation vs. Inference

Several identical hydrangea plants, each with soil of a different pH

pH 3 pH 5 pH 7 pH 9 pH 11Monitor the color of flowers over a period of several weeks or months

Page 16: Observation vs. Inference

Sci. method steps continued

• Analyze data• Publish results (results should be

repeatable)• Form a theory (possibly) A theory is a generally accepted

scientific principle

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Page 18: Observation vs. Inference

An experiment was performed to determine the effect of music on ivy plants. Two groups of plants were set up. One received music 24 hours/day, and the other was left in silence. All plants were given equal light, water and minerals.

a) Independent variable?

b) Dependent variable?

c) Constant factors?

d) Control group?

e) Experimental group?

f) Qualitative observations?

g) Quantitative observations?

Page 19: Observation vs. Inference

Radon is a radioactive gas that seeps into homes from the soil. It is thought to be one of the leading causes of lung cancer. A research team investigated this problem by collecting data from

50 homes. They measured basement radon levels, and noted how many people living in the homes had lung cancer.

a) Independent variable?b) Dependent variable?c) Control group?d) Experimental group?e) Is a placebo needed?f) Possible problems with the study?

Page 20: Observation vs. Inference

A man states that he saw Bigfoot in an isolated forest. He was alone and did not take any pictures or collect any physical evidence of Bigfoot. His observation is not very scientific because it:

a) Did not have any measurements

b) Did not have a hypothesis

c) Was not made by a scientist

d) Was not repeatable