# Week 5 Flashcards

What are the Two most common and important descriptions(summaries) of data?

• Location

• Spread (or variation)

Tells us how variable the measurements are from individual to individual

What are the measures of location?

Mean

Median

Mode

What does location inform?

Location (or central tendency)

Tells us about the average or typical individual

What does spread tell us?

Spread (or variation)

Tells us how variable the measurements are from individual to individual

What are the common measures of spread(variation)?

- Range
- Standard deviation
- Variance
- Coefficient of variation

Is the range a good estimator of the distribution width?

no

Small samples tend to give lower estimates of the range than large samples

So sample range is a biased estimator of

the true range of the population.

What is the standard deviation?

Positive square root of the variance

What is a parameter?

- Is a summary describing the population e.g. means, measures of variation, measures of relationship
- The “truth” IF you were able to measure ALL individuals in the population

What is a Statistic?

Is an approximation (estimate) of the truth, subject to error

How do precision and uncertainty relate to each other?

- High precision = low uncertainty
- Low precision = high uncertainty

What is standard error?

• Key measure of the precision of an estimate

What is the effect of increased sample size on spread?

Increasing the sample size reduces the

spread of the distribution of an estimate,

increasing precision

What does the standard error achieve?

quantifies the uncertainty around that estimate

Reflects the precision of an estimate

are Estimates with small standard errors more or less precise?

more precise than those with larger standard errors

What is the formula for the Standard error of the mean?