A questionnaire survey (アンケート) hands out a preset set of question items to many people and tallies the returned answers to see overall trends.
Because everyone gets the same questions in the same format, the answers are easy to turn into counts or percentages and compare. It can be run on paper or through a web form, so many people can be covered in a short time. On the other hand, it rarely draws out answers to questions you did not prepare, or the reasons behind an answer.
How to rememberThe Japanese word comes from the French enquête (inquiry). In English it is called a questionnaire or a survey.
Exam points
Mix-upA questionnaire survey (アンケート) collects what respondents report about themselves, while fieldwork (フィールドワーク) has the researcher watch behavior directly. Actions and habits that people are not aware of seldom show up in their answers.
An interview (インタビュー) is a survey method in which you talk directly with the people being studied, following up on their answers to draw out facts and views.
You can add or rephrase questions as you watch the other person react, so reasons and background come out. On the other hand, each conversation takes time, which makes it a poor fit for covering many people in a short period. To make good use of limited time, prepare an outline of what you want to ask beforehand.
AnalogyIt is like a doctor taking a patient's history. After hearing when the pain started, the doctor decides on the spot what to ask next.
How to rememberThe word is built from inter (between) and view (see): two people facing and looking at each other.
Exam points
ExamAn interview (インタビュー) lets you rebuild your questions on the spot to suit each person's circumstances.
ExamRecord what you hear, and after the session check the record with the other person for any misunderstanding. This prevents gaps between how the listener and the speaker understood things.
Fieldwork (フィールドワーク) is a survey method in which the researcher goes to the actual site and gathers facts by observing real work and people's behavior.
Besides observing, the researcher may join the group's activities and spend time with them. Steps and habits that the people involved never put into words can be confirmed directly on the spot. Because the researcher has to spend time on site, covering many locations at once takes a lot of effort.
AnalogyInstead of reading a recipe to learn a cook's tricks, you stand in the kitchen and watch their hands. You notice the small extra steps they forget to write down.
How to rememberField means the site or the outdoors, so think of it as research done outside the lab.
Exam points
ExamFieldwork (フィールドワーク) confirms what really happens by observing behavior or joining activities on site. It differs from Fermi estimation (フェルミ推定), which logically works out a rough figure from the information at hand.
A Pareto chart (パレート図) lines up values such as counts or amounts for each category as a bar chart sorted from largest to smallest, and overlays their cumulative percentage as a line graph.
Total the values by item
Arrange bars from the largest value
Overlay the cumulative-percentage line
Focus on the top items
The sooner the line climbs, the more the total is concentrated in a few items. Start your measures with those items.
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The cumulative percentage is found by adding values from the top item down and expressing each running total as a share of the grand total. Since it shows at a glance which items make up most of the whole, it is used to set priorities when tackling quality defects or complaints. It is counted among the seven QC tools (QC七つ道具) widely used in quality control.
How to rememberThe name comes from Pareto, an Italian economist who showed that wealth is concentrated in the hands of a few.
Exam points
ExamA Pareto chart (パレート図) shows values such as counts by cause as bars from largest to smallest, with a cumulative-percentage (累積比率) line on top. That cumulative line is what sets it apart from an ordinary bar chart.
ExamA Pareto chart is used to look at each item's share, such as counts by cause, and decide which item to act on first.
Mix-upA scatter diagram (散布図) shows the relationship between two quantities, and a histogram (ヒストグラム) shows the frequency of each interval as bars. Lining items up from largest value to smallest and overlaying the running total is the form of a Pareto chart.
ABC analysis (ABC分析) ranks items into A, B and C based on the cumulative share of a measure such as sales, and manages the important A items most closely.
Item
Sales (10,000 yen)
Share
Cumulative share
Rank
Item P
500
50%
50%
A
Item Q
250
25%
75%
A
Item R
100
10%
85%
B
Item S
80
8%
93%
B
Item T
40
4%
97%
C
Item U
30
3%
100%
C
Items are sorted from largest to smallest amount or quantity and divided by the running share added from the top (the cumulative share). The cutoffs depend on the purpose; in the table above, for example, items up to 75% cumulative are A, up to 95% are B, and the rest are C. It is used in inventory and product management to narrow down where effort should go.
AnalogyIt is like a library putting its most borrowed books on shelves near the entrance and moving rarely borrowed ones to the stacks. Effort goes to the few that move often.
How to rememberThe alphabetical order of A, B and C is the priority order. A comes first and C comes last.
Exam points
ExamABC analysis (ABC分析) ranks items by importance based on the cumulative share (累積構成比) of a measure such as sales, making clear which items to manage first.
ExamThe chart used to read off the ranks in ABC analysis is the Pareto chart (パレート図). It is used when picking the few high-value items for focused management.
Mix-upThe three classes in ABC analysis follow the size of a single measure such as sales. Its thinking differs from that of analyses that look at a subject from three viewpoints.
A cause-and-effect diagram (特性要因図) arranges the factors that affect a given result (characteristic) in the shape of a fish skeleton, branching from broad categories down to specific factors.
Characteristic: long wait at the counter
People
Not enough staff
Unfamiliar with procedures
Methods
Too many fields to fill in
Equipment
Slow terminal response
Under each category, add specific factors. In the fishbone picture these are the small bones.
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Here the characteristic is the outcome of quality or work, and a factor is anything that affects that outcome. Because factors are written out category by category, you do not stop at causes that happen to come to mind but list them more thoroughly, which makes the root cause easier to examine. Like the Pareto chart, it is one of the seven QC tools.
How to rememberFrom its shape it is also called a fishbone chart, and after its creator Kaoru Ishikawa, an Ishikawa diagram.
Exam points
ExamA cause-and-effect diagram (特性要因図) arranges the link between a result and its factors in a fishbone shape to trace the root cause.
Mix-upA cause-and-effect diagram brings out factors and organizes their relations; it does not count anything. Ranking causes by count to set priorities is the job of a Pareto chart.