Transcript accuracy__precision

Completely
missed the
dartboard!!!
I have a splitting
headache…
• Refers how close a
measurement is to
the actual (true)
value.
• Dartboard Analogy:
The bull’s eye is the
actual point where a
person is aiming for.
100g
Accurate
• “correct”. A measurement is considered
accurate if correctly reflects the size of the
object being measured.
• How close are you to the actual/accepted
value?
• Does the practice of using body parts as
measurement tools produce accurate
results?
• Refers how close a a group of measurements
are to one another. (reproducibility)
Person
1
2
3
4
5
Measurement (cm)
1.25
1.26
1.24
1.25
1.26
Precise
• A precise measurement is repeatable and
reliable. Getting the same measurement
each time.
• Does the practice of using body parts as
measurement tools produce precise
measurements? (were all of your results
the same?)
Accurate or precise?
Accurate
and
Precise!
Accurate or Precise?
neither
Accurate or Precise?
Precise
• We can never get a perfect
measurement, the best that we
can do is get as close as possible
within the limitations of our
measuring instruments.
The line falls between
23.1 and 23.2
The measurement extends
between 23.1 and 23.2
23.1?
Therefore, we can be sure the
measurement is 23.1?
This is where “estimation” comes into play…
Person
1
2
3
4
5
Measurement (cm)
st two numbers
1
1.25
(1.2_) are certain.
1.26
1.24
Last number is
1.25
(1.2?) uncertain.
1.26
Every
measurement
REQUIRES only 1
estimation!!!