# Week 5 Flashcards

1
Q

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

A

• Location
• Spread (or variation)
Tells us how variable the measurements are from individual to individual

2
Q

What are the measures of location?

A

Mean
Median
Mode

3
Q

What does location inform?

A

Location (or central tendency)
Tells us about the average or typical individual

4
Q

What does spread tell us?

A

Spread (or variation)
Tells us how variable the measurements are from individual to individual

5
Q

What are the common measures of spread(variation)?

A
• Range
• Standard deviation
• Variance
• Coefficient of variation
6
Q

Is the range a good estimator of the distribution width?

A

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.

7
Q

What is the standard deviation?

A

Positive square root of the variance

8
Q

What is a parameter?

A
• 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
9
Q

What is a Statistic?

A

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

10
Q

How do precision and uncertainty relate to each other?

A
• High precision = low uncertainty
• Low precision = high uncertainty
11
Q

What is standard error?

A

• Key measure of the precision of an estimate

12
Q

What is the effect of increased sample size on spread?

A

Increasing the sample size reduces the
spread of the distribution of an estimate,
increasing precision

13
Q

What does the standard error achieve?

A

quantifies the uncertainty around that estimate
Reflects the precision of an estimate

14
Q

are Estimates with small standard errors more or less precise?

A

more precise than those with larger standard errors

15
Q

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

A
16
Q

What does standard error imply about replication?

A

More replication is always better AS LONG AS the replicates are true replicates

17
Q

What is a Type I error?

A

– fail to reject a true null hypothesis

18
Q

What is a null hypothesis?

A

treatment has no effect on response variable

19
Q

What is a sample?

A
• A sample is one measurement taken from a single independent unit.
• Independent units do not interact.
20
Q

What is a subsample?

A

• Sometimes multiple sub-samples are averaged to make a single sample.

21
Q

What is a Replicate?

A

A replicate consists of one complete set of treatments and one control.

22
Q

define replication?

A

The process of iteratively observing multiple independent samples.