Transcript notes_precision_accuracy

Notes /Guided
Practice
Precision and Accuracy
Mean
• The mean is the average
Mean
• The mean is the average (add
up the numbers and divide by
how many numbers you
added)
Mean
• So if you had a 100, 60, and a
90 on daily work grades, then
the daily work grade would
be (250/ )
Mean
• So if you had a 100, 60, and a
90 on daily work grades, then
the daily work grade would
be (250/3) =
Mean
• So if you had a 100, 60, and a
90 on daily work grades, then
the daily work grade would
be (250/3) = 83.3
Median
• To get the median, you must
rearrange all the numbers
from smallest to largest.
Median
• Next, you must count the
numbers to see if you have an
even amount of numbers
(2,4,6) or an odd amount of
numbers (1,3,5)
Median continued
• Odd amount = number in the
middle is the median
Median continued
• Even amount of #’s = take the
average of the 2 middle
numbers and that would be
the median
Mode
• The mode is the most often
number listed.
Mode
• The mode is the most often
number listed.
• There can be 2 or more
modes.
• (END OF MICROLECTURE)
Concentration
• If you double a 0.2
concentration then you get an
0.4 concentration.
Concentration
• If you double a 0.2
concentration then you get an
0.4 concentration.
• WHAT DOES DOUBLE
MEAN?
Concentration
• If you double a 0.2
concentration then you get an
0.4 concentration.
0.2 * 2 = WHAT
Concentration
• If you had a .4 M solution,
then the concentration will
Concentration
• If you had a .4 M solution,
then the concentration will
double to 0.8
Concentration
• If you had a .4 M solution,
then the concentration will
double to 0.8
• 0.4 * 2 = 0.8
Precise
• Precise means “pretty close
together”.
Precise
• Precise means “pretty close
together”.
(3.4, 3.5, 3.6 ) are all pretty
close together…….so
Precise
(3.4, 3.5, 3.6 ) are all pretty
close together
RIGHT?…….so they are
precise
Accurate
• Accuracy (whether something
is an accurate measurement
or not) depends on what it
should have been.
Accurate
• Accuracy (whether something
is an accurate measurement
or not) depends on what it
should have been.
Accurate
• You record the mass of a 5
gram weight as 3 grams, you
are not accurate
Precise but NOT Accurate
• When you record your data
and you get (5.1, 5.2, 5.3) you
are very precise in your
measurements since
Precise but NOT Accurate
• When you record your data
and you get (5.1, 5.2, 5.3) you
are very precise in your
measurements since all your
numbers come out about the
same (which means you
measured about the
Precise but NOT Accurate
• When you record your data
and you get (5.1, 5.2, 5.3) you
are very precise in your
measurements since all your
numbers come out about the
same (which means you
measured about the
Precise but NOT Accurate
• But if the mass was actually
supposed to be 2……..you
would not be accurate
Precise but NOT Accurate
• When you record your data
and you get (5.1, 5.2, 5.3) you
are very precise in your
measurements
• (Microlecture ended)
Precise but NOT Accurate
• When you record your data and
you get (5.1, 5.2, 5.3) you are
very precise in your
measurements since all your
numbers come out about the
same (which means you
measured about the same)…..
Guided Practice
• Are these precise?
•
3.4, 3.5, 3.6
Guided Practice
• Are these precise?
3.4, 3.5, 3.6
• ARE NUMBERS close
together
Guided Practice
• Are these precise?
3.4, 3.5, 3.6
• ARE NUMBERS close
together (YUP)
Guided Practice
• Are these accurate (3.4, 3.5, 3.5) when the
target measurement was 2?
Guided Practice
• Are these accurate (3.4, 3.5, 3.5) when the
target measurement was 2?
• No….the numbers are precise (all close
together) but not accurate (not on target)
Guided Practice
• If the concentration of 0.0010 doubles, what is
the new concentration….?
Guided Practice
• If the concentration of 0.0010 doubles, what is
the new concentration….?
• 0.0020
Guided Practice
• What is the mean of (67, 28, 31, 28, 47)?
Guided Practice
• What is the mean of (67, 28, 31, 28, 47)?
• (67, 28, 31, 28, 47) = 201
• 201 / 5 = 40.2
Guided Practice
• What is the mode of (37, 13, 16, 19, 18, 13)
Guided Practice
• What is the mode of (37, 13, 16, 19, 18, 13)
• Mode = Most often listed…….13 is the most
often listed since it is listed twice
Guided Practice
• What is the median of (25, 21, 17, 24, 21)?
Guided Practice
• What is the median of (25, 21, 17, 24, 21)?
• Put it in order first (17, 21, 21, 24, 25)
Guided Practice
• What is the median of (25, 21, 17, 24, 21)?
• Put it in order first (17, 21, 21, 24, 25)
• Count the numbers (even or odd amount)?
Guided Practice
• What is the median of (25, 21, 17, 24, 21)?
• Put it in order first (17, 21, 21, 24, 25)
• Count the numbers (even or odd amount)?
Odd amount of numbers = so the number in the
middle (21)
Guided Practice
• What is the median of (17, 21, 21, 39)
Guided Practice
• What is the median of (17, 21, 21, 39)
• Numbers already in order (17, 21, 21, 39)
• Count numbers
Guided Practice
• What is the median of (17, 21, 21, 39)
• Numbers already in order (17, 21, 21, 39)
• Count numbers = Even amount of #’s
• (so take the average of the middle 2 numbers)
21 + 21 = 42
42/2 = 21
Volume
• The volume in a
graduated cylinder is
measured at the
bottom of the curve
(called the meniscus)
Volume
• The volume in a
graduated cylinder is
measured at the
bottom of the curve
(called the meniscus)
• Volume = 56 ml