Unit 1 Exam

Question 1

Mantissa
What is its rule?

Answer 1

Number of digits after the decimal in a logarithm result.
the number after the log will have the same number of sig figs as numbers after the decimal in the answer.

Question 2

X bar is…

Answer 2

Mean average

Question 3

N

Answer 3

Sample size

Question 4

Degrees of freedom

General Rule

Answer 4

N-1

You lose one degree of freedom whenever you take the average because you lose the ability to change one of the numbers

Question 5

Accuracy

Answer 5

How close you can get to the accepted value

Question 6

Precision

Answer 6

Reproducibility of the data

Question 7

How does precision affect a histogram?

Answer 7

More precision the more narrow the histogram gets

Question 8

Absolute Error

Answer 8

E
Margin of error within a particular measurement
xi-xt

Question 9

Relative Error

Answer 9

Er
Percent of total error
xi-xt/xt *100

Question 10

What are the Types of Error? Describe each.

Answer 10

Systematic- determinate, flaw, reproducible, can be eliminated
Random- indeterminate, always present, never can be eliminated, equal chance of being positive and negative
Gross- large, personal error, outliers

Question 11

Precision is due to….error
Accuracy is due to….. error

Answer 11

Random
Systemic

Question 12

What is the most common type of error and was causes it?

Answer 12

Systemic
Equipment and instrumentation, methods, personal

Question 13

Standard deviation

Answer 13

s
Used to measure how closely the data are to the mean value, the smaller the SD the closer to the mean

Question 14

Gaussian distribution results from…..errors and therefore represents the ….

Answer 14

Random
Precision

Question 15

Population
Symbol for mean average
Symbol for standard deviation

Answer 15

All measurements that are possible, infinite
µ
σ

Question 16

Sample
Symbol for mean average
Symbol for standard deviation

Answer 16

A subset of the population
x bar
s

Question 17

How many data points are needed to assume that the sample and population are the same?

Answer 17

30

Question 18

What does a negatively skewed graph tell you about the mean and median?

Answer 18

Mean< Median

Question 19

What does a positively skewed graph tell you about the mean and median?

Answer 19

Mean>Median

Question 20

What percent of data lies between +/- 1 standard deviations of the mean?

Answer 20

68%

Question 21

What percent of data lies between +/- 2 standard deviations of the mean?

Answer 21

95%

Question 22

What percent of data lies between +/- 3 standard deviations of the mean?

Answer 22

99%

Question 23

Standard Error

Answer 23

sm
Used to convey a sense of precision. something is more likely to be more precise than something else

Question 24

What are the 3 ways to convey error?

Answer 24

Standard deviation
Standard Error
95% confidence interval

Question 25

What is the variance calculation?

Answer 25

Standard deviation squared

Question 26

Relative standard error

Answer 26

RSD Provides a simple perspective on the magnitude of the data sets deviation

Question 27

Coefficient of variation

Answer 27

CV Relative standard deviation as a percent

Question 28

Confidence interval

Answer 28

the range of values within which the population mean is expected to lie with a certain probability

Question 29

Central limit theorem

Answer 29

large data sets will tend toward a normal distribution, use principle of larger sets to justify smaller ones

Question 30

T-test equation

Answer 30

allows for the calculation of confidence intervals Based on the degrees of freedom µ= x bar (+/-) (ts/(square root (N))

Question 31

What does the 95% confidence interval mean?

Answer 31

95 out of a 100 means with individually computed confidence intervals will overlap with the true mean

Question 32

What do you compare your mean average to, in order to learn about its accuracy?

Answer 32

An acceptable mean from a population (known value) A particular cutoff value (high or low) A separate experimental mean

Question 33

Null Hypothesis

Answer 33

H0 There is no difference between the quantities

Question 34

Alternative Hypothesis

Answer 34

Ha The opposite of the null hypothesis

Question 35

What is first determined in hypothesis testing? What does that value provide?

Answer 35

Confidence level (1-a) Significance level (a)

Question 36

Type 1 error

Answer 36

When the null hypothesis is rejected even though it is true. False negative

Question 37

Type 2 error

Answer 37

When the null hypothesis is accepted even though it is false False positive

Question 38

F-test

Answer 38

F= (s1^2/s2^2) Compares two means of two data sets, comparing variances

Question 39

ANOVA

Answer 39

Compares between to within, internal variances are incorporated

Question 40

What is the difference between ANOVA and a t-test

Answer 40

ANOVA includes internal variances where as t-tests assume equal or unequal variances

Question 41

Q-test

Answer 41

Exposes outliers

Question 42

Interquartile Range

Answer 42

Q3-Q1

Question 43

What are the 3 calibration methods?

Answer 43

External standards-

Question 44

ppm

Answer 44

1 µg/ 1 mL (mass of substance/mass of sample)*10^6

Question 45

ppb

Answer 45

1 ng/ 1 mL (mass of substance/mass of sample) *10^9