Ch 3 Experimental Error

Question 1

precision vs accuracy

Answer 1

precision: reproducibility of measurements
accuracy: closeness of measurement to true value

Question 2

1. centered around bullseye but not in bullseye
2. centered off bullseye but clustered

Answer 2

1. high accuracy, moderate precision
2. low accuracy, high precision

Question 3

error types
1. gross
2. systematic
3. random

Answer 3

1. gross: caused by undetected mistakes; results in outliers
2. variations reproducible + directional; fix by calibration; variations don’t avg to 0
3. variations independent + unpredictable; affects precision; variations avg to 0

Question 4

prefer low accuracy + precision vs low accuracy + high precision

Answer 4

low accuracy + high precision bc can just calibrate it

Question 5

standard deviation formula

Answer 5

s = √ [(summation di^2) / df]

di = xi - avg
df = n-1

Question 6

relative standard deviation formula

Answer 6

RSD = s/avg

Question 7

percent relative standard deviation formula

Answer 7

CV = coefficient of variation = (s/avg)*100

Question 8

variables:
1. sample mean
2. sample standard deviation
3. population mean
4. population standard deviation

Answer 8

1. x bar
2. s
3. mu
4. sigma

Question 9

pooled SD - when would you use it

Answer 9

multiple sample types within an experiment (ANOVA conditions, like my swim study)

Question 10

propagation of random error
variables: a, b, c, s(a, b, c)

Answer 10

a, b, c: values
s(a, b, c): error amount; ± value

Question 11

standard error in the mean formula

Answer 11

s(x bar) = s √(1/n)