1 Errors, Random Errors and Statistical Data in Chemical Analyses Part 1 [Sir Jameson PPT]

Question 1

Possible: __________ these errors and _____ their size with acceptable accuracy.

Answer 1

Minimize
Estimate

Question 2

The analytical results are free of errors or uncertainties.

Answer 2

Impossible

Question 3

Statistical calculations for use to judge the _______ of experimental measurements are many.

Answer 3

Quality

Question 4

________ calculations for use to judge the quality of exerimental measurements are many.

Answer 4

Statistical

Question 5

Measurements are always accomapnied by _________. The ________ always falls within a range due to uncertainty.

Answer 5

Uncertainty
True Value

Question 6

The probable magnitude of the error defines the __________ within which the true value lies.

Answer 6

Limit

Question 7

Data of unknwon quality are ___.

Answer 7

Worthless

Question 8

The __________ of measurement is never known exactly.

Answer 8

True Value

Question 9

Reliability Can Be Assessed In Several Ways

_______ of known composition can be analyzed, an the results with the known composition.

Answer 9

Standards

Question 10

Reliability Can Be Assessed In Several Ways

__________ enhances the quality of the data.

Answer 10

Calibrating equipment

Question 11

Reliability Can Be Assessed In Several Ways

Questions to answer before beginning an analysis:
- What is the ____ error that I can ________ in the result. No one can afford to waste time generating data that are more reliable than is needed.

Answer 11

Maximum
Tolerate

Question 12

Measures of Central Tendency

2 types measures of the location of the middle of a distribution.

Answer 12

Mean
Median

Question 13

_________, artithmetic mean, and average (x) are synonyms.

Answer 13

Mean

Question 14

The Mean and Median

where __ represent the individual values of x making up a set of N replicate measurements

Answer 14

Xi

Question 15

The Mean and Median

The symbol _______ means to add all the vlues Xi for the replicates.

Answer 15

EXi

Question 16

it is the middle result when replicate data are arranged in order of size.

Answer 16

Median

Question 17

Equal numbers of results are _____ and _____ than the _________

Answer 17

Larger and Smaller
Median

Question 18

For an odd number of ________, the __ can be evaluated directly.

Answer 18

Data points
Median

Question 19

The _______ of two or more measurement is their ________ value.

Answer 19

Mean
Average

Question 19

For an ______, the ______ of the middle pair is used.

Answer 19

Odd number
Median

Question 19

The median is used advantageously when a set of data contains an ___________, a result that differes significantly from others in the set.

Answer 19

Outliers

Question 19

It describes the reproductibility of measurements; the closeness of results to each other.

Answer 19

Precision

Question 19

It is determined by repeating the measurement on replicate samples.

Answer 19

Precisions

Question 20

Three terms of describe the precision of a set of replicate data:

Answer 20

Standard Deviation
Variance
Coefficient Of Variation

Question 21

It is function of the deviation from the mean di, or just th deviation, which is defined as

Answer 21

Precision

Question 22

Precision Formula

Answer 22

di = | Xi - x̄|

Question 23

It is closeness of results to others that have been obtained in exactly the same way.

Answer 23

Precision

Question 24

It indicates the closeness of the measurement to its true or accepted value and is expressed by the error.

Answer 24

Accuracy

Question 25

It measures agreement between a result and its true value

Answer 25

Accuracy

Question 26

It describes the agreement among several results that have been obtained in the same way.

Answer 26

Precision

Question 27

in the measurement of a quanity Xi, is given by the equation.

Answer 27

Absolute Error E

Question 28

Absolute Error Formula

Answer 28

E = Xi- Xt

Question 29

It is more useful quantity thant the absolute error.

Answer 29

Relative Error

Question 30

Relative Error Formula

Answer 30

Er= Xi - Xt divided by Xt times 100%

Question 31

An error is also expressed in parts per thousand (ppt)

Answer 31

Relative Error

Question 32

To determine ________, we have to know the ______, and this value is exactly what are we seeking in the analysis.

Answer 32

Accuracy
True Value

Question 33

it can be precise without being accurate and accurate without being precise

Answer 33

Results