Database Reference
In-Depth Information
nals in the data, as well as save time and effort by filtering out the noise. When creating con-
trol charts, users can either opt to employ the quick method or the rigorous method, depend-
ing on their level of skill and the degree of statistical rigor warranted by the situation.
Figure 7-16. A monthly view of global earthquakes using the rigorous method
Understanding Uncertainty
When we present data to an audience, it's important to make clear whether we are presenting
data from the entire population, or from just a sample of the population.
Often, the data set we're working with is the whole enchilada—all sales for the past quarter,
total inventory levels, a team's win percentage for the entire season. But sometimes we're
only presenting data from a sample of the population—quality inspection results for a sample
of the day's production, or the results of a customer satisfaction survey sent to 1% of the cus-
tomer base.
