The document discusses accuracy, precision, and errors in analytical measurements. It provides examples showing that accuracy refers to how close a measured value is to the true value, while precision refers to the consistency of repeated measurements regardless of accuracy. There are three main types of errors: determinate (systematic) errors which can be identified and corrected, indeterminate (random) errors which are unpredictable, and gross errors resulting from major mistakes. Sources of errors include faulty equipment, improper technique, and environmental fluctuations. Methods for minimizing errors include instrument calibration, control determinations, blank tests, cross-checking results, and using standards.

1. ACCURACY , PRECISION AND ERRORS

2. ACCURACY PRECISION

3. Tablet containing Diclofenac sodium 50 mg
(True value)
ACCURACY
PRECISION
Analyst - 1 Analyst - 2
50.01
50.02
50.03
50.04
50.05
50.06
---------
50.05
--------
41.01
42.01
41.09
41.08
41.07
41.08
---------
41.22
--------
The average value got by the Analyst – 1 is close to true value
The variation between the true value and the average value
by Analyst – 2 is high.
The values obtained is close to
each other, but not close to true.
It is otherwise called as
Repeatability.

4. ACCURACY:
Is defined as the closeness of a measured value to the true value
PRECISION:
Is defined as the variation between the true value and the measured value is
high,
So it is not accurate,
But the obtained values are close to each other it shows the repeatability,
called Precision

5. ERRORS
It is defined as ,”the difference between the measured value and true value”
Or
Any deviation from the true value is termed as Error…
It is impossible to completely eliminate an error, while making measurements,
even when specialized hand and apparatus are employed
Errors can be minimized by understanding its magnitude…
TYPES
Determinate Error
(Systematic Error)
Indeterminate Error
(Random Error)
Gross Error

6. Determinate Error (Systematic Error)
e.g. Errors in titration
These errors can be prevented or minimized
Identification and correction of the systematic errors is possible…
Sources of Systematic Errors:
Incorrect formulas used for calculation
Different analytical methods are used
Errors produced during sampling
An error caused due to weighing wrong amount of sample
Incorrect concentration of titrant
Sensor not adjusted properly
Titration performed at high speed for a chemical reaction…

7. Indeterminate Error (Random Error)
This errors are unpredictable and difficult to identify
Sources of Random Errors:
Samples handled improperly
Inefficient equipment
Presence of bubbles in burette and pipette
Improper washing after each sampling
Less trained operators
Fluctuation in environmental conditions like temperature and humidity…

8. Gross Error
Is the combination of both systematic and random errors
They are the result of high mistakes made during analysis and can be
identified easily
Gross errors are also termed as “Avoidable Mistakes”
Sources of Gross Errors:
Notation mistakes
Calculation errors
Mix-up of samples or reagents
Wrong sample size
Misunderstanding in instrumental operation
“Proper training and care from analyst can minimize these errors”

9. Methods of Minimizing Errors
Calibration of instruments and apparatus – and applying necessary corrections
Performing parallel control determination
Blank determination
Cross – checking results by different methods of analysis
Methods of standard addition
Method of internal standard…

10. THANK YOU