3. STATISTICS

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Why?

- Because we can't sample every part.

- Because no matter what we do, no two parts will be the same.

- Because we define a product to meet specifications and we can measure how well it conforms.

- Because differences between parts are hard (assignable causes) or impossible (chance causes) to predict.

- Because we can sample a few and draw conclusions about the whole group.

What is the objective?

- We want to sample as little data as possible to draw the most accurate conclusions about the distribution of the values.

Two type of statistics

- Inductive - Try to get overall variance within group. i.e. assume all of group should conform ***WE USE THIS TYPE

- Deductive - Attempt to classify differences that exist within a group (i.e. election polls).