chapter 4: statistics

Question 1

what does statistics allow us to do

Answer 1

1, accept conclusions
2. reject conclusions

Question 2

what is the mean

Answer 2

the average

Question 3

what is the standard deviation

Answer 3

measures how closely the data are clustered around the mean

Question 4

what does a small standard deviation mean

Answer 4

the more closely it is clustered around the mean

Question 5

what is precision

Answer 5

reproducibility

Question 6

what is accuracy

Answer 6

the nearness to the truth

Question 7

experiments with a small SD are more…

Answer 7

precise

Question 8

greater precision does not mean

Answer 8

greater accuracy

Question 9

what form should you express the mean and SD

Answer 9

mean +-standard deviation(n=)

Question 10

what is special about the average and the SD

Answer 10

they should end in the same decimal place

Question 11

how do you find the degrees of freedom

Answer 11

n-1

Question 12

what is variance

Answer 12

the square of the standard deviation

Question 13

what is the relative standard deviation

Answer 13

standard deviatin expressed as a percentage of the mean

Question 14

what is the equation for relative SD

Answer 14

s/x x100

Question 15

what is the equation for the gaussian curve

Answer 15

Question 16

what happens as an experiment is repeated more times

Answer 16

the results approaches an ideal gaussian curve

Question 17

if there is an infinite set of data what happens to the mean and the standard deviation

Answer 17

it becomes (U symbol)
it becomes the circle symbol

Question 18

what is the equation for a z score

Answer 18

Question 19

what does the area under the curve add up to

Answer 19

1

Question 20

what happens if there is a larger standard deviation

Answer 20

the broader curve

Question 21

what is the equation of the standard deviation of the mean

Answer 21

standard deviation/ square root (# number of measurements)

Question 22

what is the null hypothesis

Answer 22

states that two sets of data are drawn from populations with the same properties

Question 23

when will we reject a null hypothesis

Answer 23

if there is less than 5% probability of observing the results

Question 24

what tests do we use for a null hypothesis

Answer 24

1. f test
2. f test

Question 25

what does the f test compare, what does the t test compare

Answer 25

1. standard deviation
2. the mean

Question 26

what is the formula for f test

Answer 26

(s1)^2/(S2)^2
- put the larger SD on top so the numerator is more than 1
-Fcalc> Ftable = reject, difference is significant

Question 27

what is the equation to calculate confidence intervals

Answer 27

mean +- ts/square root n