Scientific Method Observation vs. Inference

Observations• Any information collected with the senses (the skill of

describing scientific events!) • Quantitative – measureable or countable

» 3 meters long» 4 marbles» 50 kilograms» 35 degrees Celsius

• Qualitative – describable, not measureable » red flowers» smells like fresh baked cookies» Tastes bitter

Science begins with observations..

• Qualitative observations: describe physical qualities, which include color, shape, and texture. (descriptive) *Remember “Quality”

• Quantitative observations: involve measurements of length, volume, mass, etc. taken with a ruler, graduated cylinder, balance, or other measuring device. (n=numbers)

Example:Qualitative observations: Carmel color skin, black hair, muscular arms with tattoos, mustache, etc.

Quantitative observations: Height: 1.91 m (191 cm)Weight: (86 kg)Arm span: 1.90 m (190 cm)

Inference (different from observations)

• Observations: information that is directly seen or measured.

• Inference: an assumption based on judgment or previous experience.– Conclusions or deductions based on observations.– The process of drawing a conclusion from given evidence.

• Examples:• Observation-that coconut is very round.• Inference-that coconut would make some good

coconut juice.

Some examples of inference are:

• Sherry's toddler is in bed upstairs. She hears a bang and crying. Sherry can infer that her toddler fell out of bed.

• John hears a smoke alarm and smells burnt bacon. John can infer that his neighbor burnt her breakfast.

• Norman sees cookie crumbs on the floor and chocolate around his son's mouth. Norman can infer that his son got into the cookie jar.

• Bob eats salad for lunch each day and is a PETA member. His co-workers can infer that he is a vegetarian.

• At 5 o'clock Jill saw her assistant's office light out and did not hear the sound of typing. Jill can infer that her assistant went home.

• After her guests went back for second helpings, Mary could infer that they enjoyed her meal.

Inferences are made all the time, every day. By reviewing these examples of inference you can probably better identify them when you see inferences for yourself.

Practice: Observation OR Inference?

1) I hear people screaming2) I smell cotton candy, popcorn, and

hamburgers3) That glass of clear liquid is water4) I see a lot of people5) That old man is a grandpa

Look at these two sets of animal tracks.

List 3 OBSERVATIONS

Make an INFERENCE

Make 3 OBSERVATIONSMake an INFERENCE

Now what do you think?

Now what do you think?

Make 3 OBSERVATIONSMake an INFERENCE