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STAR*NET V6 - Circe

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Chapter 8 Analysis of Adjustment Output<br />

8.11 Adjusted Observations and Residuals (Optional)<br />

<strong>STAR*NET</strong> next lists all adjusted observations and their residuals. A residual is the<br />

difference between the observed value and the corresponding value computed from the<br />

adjusted coordinates. The sizes of the residuals are an indication of how well your<br />

observations have fit into the adjusted network. The observation standard errors you<br />

specified are also listed to show you how much weight each observation had in the<br />

adjustment. Although this section of the listing is optional, it is an important one that you<br />

normally will want included.<br />

Adjusted Observations and Residuals<br />

===================================<br />

Adjusted Angle Observations (DMS)<br />

At From To Adj Angle Residual StdErr StdRes<br />

1 701 2 123-40-27.22 -0-00-00.12 4.55 0.0<br />

2 1 3 217-11-36.03 -0-00-00.94 4.99 0.2<br />

3 2 4 113-53-19.28 0-00-21.27 5.18 4.1*<br />

Adjusted Distance Observations (FeetUS)<br />

From To Adj Dist Residual StdErr StdRes<br />

1 2 537.5551 0.0351 0.0211 1.7<br />

2 3 719.5360 0.0260 0.0273 1.2<br />

3 4 397.6922 0.0322 0.0202 1.5<br />

Adjusted Observations and Residuals<br />

You should examine the residuals carefully to see whether they appear reasonable.<br />

<strong>STAR*NET</strong> computes an additional value called the Standardized Residual (StdRes),<br />

which is equal to the residual divided by its standard error. This ratio takes into account<br />

the different types of observations (i.e. angles and distances) and the different units of<br />

standard error (i.e. seconds and feet) assigned to them, and and lets you easily make<br />

comparisons of the changes to all observations as “Standardized” residuals.<br />

You can also think of this value as the ratio between your observation’s actual fit in the<br />

adjustment (its residual), and your estimate of the strength (your input standard error). If<br />

the ratio is less than 1.0, it actually fit better than you had estimated. If it is larger than<br />

one, it didn’t fit as well. However, Standardized Residuals usually have a value greater<br />

than 3.0 before we can really say that there is a problem. Values greater than 3.0 are<br />

flagged with “*” to help you locate them quickly.<br />

The cause of any flagged values should be investigated. However, no observation should<br />

be deleted until a good reason is found for the problem. A large residual in a particular<br />

observation may be the result of a blunder in some other observation.<br />

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