Topic 3 Theory Of Errors In Observations

Question 0

Facts about Measurements

Answer 0

Never exact
Contains an error
True value is never known
Exact error in measurement is always unknown

Question 1

Facts About Errors

Answer 1

Errors area present in all measurements.
The surveyor is concerned with the RANGE OF ERROR.
The error is the difference between the measured value and the true value. AKA: RESIDUAL
Errors can mostly be adjusted by computations. Cannot adjust MISTAKES!

Question 2

Types of Measurements

Answer 2

Horizontal
Vertical
Slope Distances
Horizontal Angles
Vertical Angles

Question 3

SOURCES of Errors

Answer 3

Person, instrument, and environment

Question 4

TYPES of Errors

Answer 4

Systematic Errors
Random/accidental errors
Blunders or mistakes

Question 5

Dealing with Errors and Mistakes

Answer 5

Errors can be minimized by:
  -calibrating equipment
  -following good observation practices
  -correcting for atmospheric variations
Mistakes should be avoided at all costs. Only have to return to the field to correct them. Always check measurements for mistakes.

Question 6

MVP

Answer 6

Most Probable Value - mean

Question 7

Residuals

Answer 7

The difference between any observed value of a quality and the MPV.

R = measurement - MPV

Question 8

Precision Ratio

Answer 8

A way to specify acceptable tolerances for linear measurements. Used specify positioned closure for traversing.
1:N
N is truncated to the lower multiple of 100 or 1000.
The higher the value of N, the higher the order of survey.

Question 9

Propagated Error

Answer 9

Quantities computed from measurements contain a propagated error. For example:

• error due to sum estimation
• error due to series estimation
• error of a product
• error in the mean