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  1. #1

    Default Reducing error with large surveys

    Had a discussion that suggested there is a higher probability of error when there is a group of people surveying a site versus a single surveyor, and there was some data to support it. What things can be done to increase survey reliability and reduce error when there are multiple surveyors collecting data.

    1) Potential surveyors to a project survey a known loop to check for accuracy
    2) Same equipment- have seen some error between compasses that can add up when approaching 1000s of feet
    3) a chief surveyor of a project checking segments and doing backward shots

    others?

    "Not all change is improvement...but all improvement is change" Donald Berwick

  2. #2

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    Two thoughts.

    Changing the goal of the survey to be accuracy and data richness instead of big numbers per dive would be a huge a step forward for the dive community.

    Rather than trying to reinvent the wheel, cave divers could simply adopt the same procedures used by the Cave Research Foundation in dry cave surveys. They adopt many of the techniques suggested above in their management of large cave surveys, particularly in National Parks. All surveyors and instruments are checked via repeating high accuracy surveys. There is also an emphasis on accurate, detailed sketching, which is vital to resource management. As a cave scientist, I can say that stick maps are slightly better than worthless for understanding caves.

    Jason Gulley

  3. #3

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    Quote Originally Posted by jason View Post
    Two thoughts.

    Changing the goal of the survey to be accuracy and data richness instead of big numbers per dive would be a huge a step forward for the dive community.

    Rather than trying to reinvent the wheel, cave divers could simply adopt the same procedures used by the Cave Research Foundation in dry cave surveys. They adopt many of the techniques suggested above in their management of large cave surveys, particularly in National Parks. All surveyors and instruments are checked via repeating high accuracy surveys. There is also an emphasis on accurate, detailed sketching, which is vital to resource management. As a cave scientist, I can say that stick maps are slightly better than worthless for understanding caves.
    I agree standardization is critical,but having accuracy with the tools that are being implemented is important. I have seen some surveyors enter a project with minimal to no experience,and this enters a lot of error. A mentorship/apprenticeship methodology would be good to help develop skill with the equipment and technique.

    "Not all change is improvement...but all improvement is change" Donald Berwick

  4. #4

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    I think one of the biggest ones these days is going to be whether the surveyors factored in compass declination if they are using a combination of digital and analog compasses. It's only about 5* depending on where in cave country you are, but that can be considered a big error


  5. #5
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    Default

    Correct your survey with cave radio location at some interval.


  6. #6

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    Quote Originally Posted by PfcAJ View Post
    Correct your survey with cave radio location at some interval.
    That's not often practical. There are landowner issues, power line and building locations, dense foliage that can restrict radio location.

    Surveyors can, however, complete large loops and assess their survey against the standard survey for the loop prior to being allowed to contribute data to large projects. Any time a new instrument is used, it should be tested against the standard loop.

    Front sights and back sites also help catch errors.

    So, basically all of the ideas that Kelly tossed out....

    Jason Gulley

  7. #7

    Default

    Quote Originally Posted by Kelly Jessop View Post
    I agree standardization is critical,but having accuracy with the tools that are being implemented is important. I have seen some surveyors enter a project with minimal to no experience,and this enters a lot of error. A mentorship/apprenticeship methodology would be good to help develop skill with the equipment and technique.
    Mentorship is extremely helpful. I learned to survey in dry caves by surveying alongside experienced teams. I started by holding the dumb end if the tape and being directed to useable station locations. Later, I started reading a duplicate set of instruments alongside the team. Once I was able to duplicate their results, I was able to read instruments on my own. I later did the same thing with sketching.

    Jason Gulley

  8. #8

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    Quote Originally Posted by PfcAJ View Post
    Correct your survey with cave radio location at some interval.
    The bad thing is that I have seen some huge error in this. If the transmitter isn't level, even if you triangulate you will be way off. Even operator error because there is a learning curve involved. I remember when I first learned radio locates I could swear I was at the null,but someone would show me my operation error. Even if you use radio locates to make things "fit", and line up with the sinks, is it really correct?

    "Not all change is improvement...but all improvement is change" Donald Berwick

  9. #9
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    Default

    Quote Originally Posted by Kelly Jessop View Post
    The bad thing is that I have seen some huge error in this. If the transmitter isn't level, even if you triangulate you will be way off. Even operator error because there is a learning curve involved. I remember when I first learned radio locates I could swear I was at the null,but someone would show me my operation error. Even if you use radio locates to make things "fit", and line up with the sinks, is it really correct?
    No method is perfect and all methods have a learning curve and the potential for human error.


  10. #10

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    Quote Originally Posted by PfcAJ View Post
    No method is perfect and all methods have a learning curve and the potential for human error.
    Agree, and hence the reason for the thread. For big projects which have a lot of people involved, what can be done to reduce the error. The radio locates are a great tool, and have learned there are things that can be done to increase the accuracy.

    "Not all change is improvement...but all improvement is change" Donald Berwick


 

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