The Pareto chart is based on the
principle named after an Italian economist Vilferdo Pareto who observed that
80% of land in Italy in the early 1900’s was owned by 20% of the population. A Pareto
is a bar graph. The lengths of the bars represent frequency or cost(time or
money) and are arranged with longest bars on the left and shortest to the
right. In this way, the chart was visually depicts which situation are more
significant.
·
When
using Pareto chart :
Ø When analyzing
data about the frequency of problems or causes in a process.
Ø When there are
many problems or causes and you want to focus on the most significant.
Ø When analyzing
broad causes by looking at their specific components/
Ø When
communicating with others about your data.
·
Pareto
chart procedure :
Ø Decide what
categories you will use to group items.
Ø Decide what
measurement is appropriate. Common measurement are frequency, quantity,cost and
time.
Ø Decide what
period of time the Pareto chart will cover one workcycle? One full fay? A week?
Ø Collect the
data, recording the category each time.
Ø Subtotal the
measurements for each category.
Ø Determine the
appropriate scale for the measurement you have collected. The maximum value
will be the largest subtotal from steps. Mark scale on the left side of chart.
Ø Construct and
label bars for each category. Place the tallest at the far left, then the next
tallest to its right and soon. If there are many categories with small
measurements, they can be grouped as “others”.
Ø Calculate the
percentage for each category, the subtotals for the category divided by the
total for all percentage. Draw right vertical axes and label it with percentages.
Be sure the two scales match. For example, the left measurement that corresponds
to one-half should be exactly opposite 50% on the right side.
Ø Calculate and
draw cumulative sum: Add the subtotals for the first and second categories, and
place a dot above the second bar, indicating that sum. To that sum add the
subtotal for the third category and place dot above the third bar for the new
sum. Continue the process for all the bars. Connect the dots, starting at the
top of the first bar. The last dot should reach 100 percent on the right scale.
Collected
from Google
Collected
by: Sony Maharjan( Team Samarpan, SEE graduate 2073)
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