Precision vs Accuracy

1
Precision vs Accuracy

1. Review Concepts
2. Perform Activity
3. Record Data
4. Beginning of next class Generate
   Box-and-Whiskers Graph

2
High Accuracy Low Precision

• Accuracy is correctness.
• Check by using a different method.
• Poor accuracy results from procedural or
  equipment flaws.

3
High Precision Low Accuracy

• Precision is reproducibility.
• Check by repeating your experiment.
• Poor precision is due to poor technique.

4
Box and Whiskers GraphsWhat it is

• Five-number summary or Boxplot are other names
  for the visual representations of the
  box-and-whisker plot.
• It consists of the median, the quartiles, and the
  smallest and greatest values in the distribution.
  
• Immediate visuals of a box-and-whisker plot are
  the center, the spread, and the overall range of
  distribution.

5
Box and Whiskers GraphsOrganizing the Data

• The first step in constructing a box-and-whisker
  plot is to first find the median, the lower
  quartile and the upper quartile of a given set of
  data.
• Example The following set of numbers are the
  amount of marbles fifteen different boys own
  (they are arranged from least to greatest).
• 18 27 34 52 54 59 61 68 78 82 85 87 91 93 100

6
Box and Whiskers GraphsFinding the Median

• First find the median. The median is the value
  exactly in the middle of an ordered set of
  numbers.
• 18 27 34 52 54 59 61 68 78 82 85 87 91 93 100
• 68 is the median

7
Box and Whiskers GraphsFinding the Lower
Quartile

• Next, we consider only the values to the left of
  the median 18 27 34 52 54 59 61.
• We now find the median of this set of numbers.
• Remember, the median is the value exactly in the
  middle of an ordered set of numbers.
• Thus 52 is the median of the scores less than the
  median of all scores, and therefore is the lower
  quartile.

8
Box and Whiskers GraphsFinding the Upper
Quartile

• Next, we consider only the values to the right of
  the median 78 82 85 87 91 93 100.
• We now find the median of this set of numbers.
• The median 87 is therefore called the upper
  quartile.

9
Box and Whiskers GraphsGraphing the Extreme
Values

• Lastly, we look at the lowest and the highest
  values recorded, in this case 18 and 100.
• We draw single lines connecting our Box to our
  extreme data values.
• These extremes are referred to as the Whiskers

10
Graph your own data

• Using the graph paper provided, graph the data
  collected during the precision vs. accuracy lab
  activity
• Once you and your partner have completed your
  graphs (two separate graphs for the 1 meter and 2
  meter data),
• Bring your graph to the board and follow the
  instructions given.