Since time truly is money in the surveying business, the goal is to reduce random error inherent in survey measurements. The founding fathers of the Deft School are Prof Tienstra, Prof Baarda and indeed Prof Teunissen (whose class mate I was back in the eighties).For most surveying projects, speed, efficiency and accuracy of measurements are paramount. In effect it means that your QC results are consistent all the way.

That's all of the typicality of the Delft School in a nutshell. You may also translate this requirement into the following formulation: the reliability in connection with one-, two-, three-, or multidimensional tests is always the same. This relation should be consistent and should not in any way depend on whether you look at one-, two, -three or multi-dimensional tests. Now back to the Delft School: As we have seen, precision, reliability and testing are interrelated. For instance MOVE3 gives the maximum coordinate shift for each critical (or marginally detectable) error. I may then ask myself: what influence has this (assumed) error on the coordinates? This is called external reliability and it can be expressed in various ways. This means, I haven't been able to detect it by testing. Let us assume that an error is made in an observation with a value just below the critical (or marginally detectable) value. The second question follows from the previous. Note that here you can a lot to improve the quality of your work, typically by applying a better network design and/or by a better precision of your measurements. Its value can be computed for each individual observation. My common sense says, if the error is really big I will definitely detect it, but how big should it be at least, for my test to say 'Rejected'? This is called 'internal reliability' and is expressed by the so called marginal or critical detectable error. Some observations may contain errors which I have not identified. Q1: having performed the testing procedures with care, I now know that the result cannot be interpreted as absolute truth. *RELIABILITY => deals with two interesting questions on the network as a whole, typically Chi square or normalize Chi-sqaure) can be performed. on 3-D coordinates or GPS baselines) or multi-dimensional tests (e.g. on state plane coordinate pairs) or three dimensional teste (e.g. Note that tests referring to individual observations are one-dimensional (data snooping).

You may only say 'this observation is correct' when you add to it 'with a 95% probability'. Bottom line: testing results have a statistical character. False negatives occur if an observation containing a real error is accepted by the testing procedure.

False positives occur if an observation is rejected while in reality there is nothing wrong with it. In general one tries to avoid 'false positives' or 'false negatives' as much as possible. * TESTING => procedures to identify possible errors in your observations. It is a result of your instruments' specifications and, of course, you should take your observations under good conditions. Precision is something you cannot do much about. * PRECISION => the propagation of measurement noise (not errors) into the coordinates. The specialty of the Delft School lies in the quality control. Least squares is least squares, That is when it comes to coordinate computation in regular (1D, 2D or 3D) survey networks. There is nothing mysterious about the 'Delft School'. Related Question for the Resident Geodesists I would appreciate hearing from anyone who uses Move3 a lot. I am willing to pay for an excellent program that is being maintained and improved all the time. Some might think that Move3 is pricey, but for the type of work I do I use LSQ everyday, it is a critical component to my work. I cannot recommend Geolab to anyone anymore because of this. To me, it is very unfortunate that such a great program (Geolab) has stagnated.

Well, since then it has done the same thing on 3 computers and my laptop. I reported this to him, he said it must be the graphics card on my computer. One issue I have with it is that I cannot view network diagrams, it causes the program to blow up. The developer always promises that there is a new release coming soon, but it never happens. It is a very robust program, and I trust the results. They seem to be very responsive to suggestions and bug reports. But, I do follow them on linkedin, and I see that they are constantly making improvements. I had a lot of problems getting it to work they way I wanted it to. I did buy a demo ($149, they send you a key to use for 60 days) a few years ago, at that time I didn't like it enough to make the change from Geolab.

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