Measurement Errors

Question 1

What is a systematic error?

Answer 1

Your mistakes
Incorrect instrument calibration
Pipetting error
Changes in experimental condition

Question 2

What is a random error?

Answer 2

Reading errors
Sampling errors
Intrinsic variability - esp in biology

Question 3

What does the reading error tend to be?

Answer 3

+/- half of the smallest division

ie 23 +/- 0.5mm on a ruler

Question 4

Reading error takes into account biological variability

True/false

Answer 4

False

Question 5

How do you work out the standard error of a count?

Answer 5

Square root of the number found

Question 6

What is a sample in biology?

Answer 6

Specimen

Question 7

What is a sample in stats?

Answer 7

Subset of numbers/population to analyse defined by a statistical parameter

Question 8

What is a statistical estimator?

Answer 8

Sample attribute used to estimate a population parameter

Question 9

Which value is more appropriate for skewed distributions: median or mean?

Answer 9

Median

Question 10

The median is not sensitive to outliers true/false

Answer 10

True

Question 11

Which is more appropriate for normal distribution: mean or median?

Answer 11

Mean

Statistical tests on this are more powerful than non-parametric tests

Question 12

What is the standard deviation?

Answer 12

Measure of a spread of data points

Question 13

Standard deviation depends on sample size

True/false

Answer 13

False

Question 14

Standard error can be improved by decreasing sample size

True/false

Answer 14

False