Missing the mark--known in biblical Hebrew as chata[1] and in our modern vocabulary as sin--is committed by land surveyors every day.

That’s right! Land surveyors commit sin every time the precise measurements that they make pursuant to boundary retracement miss the actual target that should be in their sights--the property boundary lines in question. This situation occurs because we either don’t know the difference between precision and accuracy or we have forgotten the difference through our blind worship of the god of measurement.

The god of measurement has bestowed upon us RTK-GPS, robotic total stations and laser measuring devices with which to worship him. In return, he has blinded us to the reality that precise measurements do not mean accurate measurements. Our other senses have been dulled, as well. Now we expect all things to bow to our precision (monuments in particular). If they don’t, then these things are not accurate, and that means they are wrong. There is only one god greater than the god of measurement--the god of deeds. She tells the god of measurement what to do.

Our Collective Confusion

Being accurate has almost nothing to do with measurements, especially when the subject matter is boundaries, but it’s little wonder we are confused. Our own standards often confuse these concepts. They refer to relative accuracy of measurements when they should be referring to relative precision. For example, the Standards of Practice for Surveying in the State of Alabama[2] states: “The accuracy of the measurements shall be statistically verified by the results of a closed traverse.”[3] It then goes on to explain “permissive” relative error of closure ratios. These are precision ratios. They are a measure of how precisely we turned our angles and measured our distances in the field. They have nothing to do with being accurate.

We are not alone in our confusion. Every standard I have had an opportunity to look at is equally confused. Let’s take the ALTA/ACSM Standards as another example. The last page is entitled “Accuracy Standards for ALTA/ACSM Land Title Surveys.” The first sentence says it all: “These Accuracy Standards address Relative Positional Accuracy for measurements that control land boundaries on ALTA/ACSM Land Title Surveys.”4 Don’t we really mean precision and not accuracy? When the standard discusses the relative position of any given point being 0.07 feet plus 50 parts per million, aren’t we talking about how precisely we measured those points in the field and the expectations one is to have when retracing our work? To say that our work is accurate is a different subject altogether. We can precisely measure the monuments in the field and verify these measurements against a ratio or a standard, but if the measurements are made to the wrong monuments, then they are completely inaccurate.

Figure 1- High Accuracy/Low Precision

Accuracy vs. Precision

Don’t get me wrong. I understand what these standards are trying to say. They are trying to say that our measurements are true measurements and are therefore accurate. The problem is that what’s true in the context of boundary retracement has very little to do with measurements. The implication is that since your measurements are true, so is your boundary opinion. The landowners and courts are concerned with accuracy, not precision. When we tell them that our survey is accurate, they think we have accurately defined the boundaries when in reality what we have done is precisely measured between monuments.

Wikipedia defines the terms this way: “Accuracy is the degree of veracity while precision is the degree of reproducibility.”[5] In other words, accuracy is the measure of the truth of the matter while precision is how well we made our measurements.

The difference between accuracy and precision can be easily illustrated by the target analogy. The bull’s-eye on both targets in Figures 1 and 2 represents 100-percent accuracy. The four shots in Figure 1 are highly accurate (close to the bull’s-eye) but not very precise because of the spread of the pattern. In contrast, Figure 2 shows four very precise shots in a tight pattern that demonstrates repeatability, but they are not accurate shots because they have missed the mark. To put this in land surveying terms, Figure 1 represents a survey of property that doesn’t have a very good closure--say, 1 foot in 10,000--but the true corners and the true boundary lines were recovered and identified. Figure 2 represents a survey with a tight closure--say, 1 foot in 100,000--but the wrong property was surveyed. If accuracy and precision are both achieved, then the results are considered valid. When it comes to surveying property, however, accuracy is everything--precision is nice but somewhat meaningless.

Figure 2- High Precision/Low Accuracy

Now that we have examined these confused concepts, we arrive at the surveyor’s paradox. Accuracy is not dependent on precision, but we depend on precision as our test for accuracy. We find an existing monument at a property corner. The god of measurement tells us that it’s not accurate because it does not match the precision required by the god of deeds. We set a new monument with new precise measurements and call the survey accurate. But if the existing monument was the property corner, how can the survey be accurate?

The same can be said for the center 1/4 corner. We find a monument at the center 1/4, but because it’s not at the intersection of straight lines drawn through the opposing 1/4 section corner as determined by our precise measurements, it’s not accurate and a new monument must be set. But if the existing monument is the center 1/4, how can it not be accurate? Can anyone say “pincushion”? Pincushions are the surveyor’s answer to the contradiction.

The Courts Aren’t Confused

The courts are not confused by these concepts. If a boundary dispute comes into court, and the court correctly applies the law, it will render a decision about the boundaries that is 100-percent accurate without ever making one measurement. And do not fool yourself. The courts expect us to bring in surveys of property that are accurate. They could really care less about precision. As stated in the case of Andrews v. Barton, “The purpose of the surveys in this boundary dispute is to locate accurately the boundary between the plaintiff’s and defendants’ property.”[6] Unfortunately, we focus way too much on precision--in some cases, to the exclusion of accuracy.

In the Andrews v. Barton case, Andrews’ surveyor was asked to survey three lots in a subdivision block containing 50-foot wide lots. The surveyor precisely measured the block and determined that it was 50 feet short. The surveyor then proceeded to prorate the shortage throughout the block, completely eliminating Barton’s lot in the process. This, in the surveyor’s mind, was an accurate survey. The problem wasn’t that the block was 50 feet short. The problem was that Andrews’ predecessor in title had sold one of his lots (the last lot on the end of the block) to the county for a road right-of-way, eliminating an entire lot from the block. Andrews’ survey, as precise as it may have been, was totally inaccurate. The court was looking for an accurate survey, not a precise one.

Title companies also require an accurate survey to lift the survey exception from a title policy. Typical language from the Schedule B-2 exceptions refers to those matters that would be revealed by an accurate survey. The ALTA/ACSM Standards refer to how accurate our surveys are. We certify on those ALTA/ACSM surveys that our survey meets certain “Relative Positional Accuracy.” What are we really saying? Are we saying that we’ve got the true and correct (accurate) boundary corners (represented by monuments) within 0.07 feet plus 50 parts per million, or are we saying that the monuments we are showing have been precisely measured? If we are saying the former, then we have an accurate survey. If we are saying the latter, then we have a precise survey that may or may not be accurate. The sad reality is that many of us really don’t care−our precise measurements render our survey accurate regardless of whether we have actually surveyed the true boundaries.

Time to Refocus (and Repent)

We’ve got the precision thing down. Trained technicians can make precise measurements with the equipment we have today. It’s time to refocus our attention, especially when it comes to property boundary work, to the professional tasks at hand.

If you have technicians working for you, let them make the precise measurements, run the closures and tell you precisely where things are in relation to one another. Your job needs to be in conducting the evidence-gathering process, evaluating that evidence and forming a well-reasoned opinion on the boundary lines involved. This requires not only dealing with the facts and things that have been gathered, but with the people, the situation and the ideas that are in play. It also requires understanding the difference between precision and accuracy. Both can be achieved, thereby rendering your results valid.

Practicing these principles doesn’t end the problem, however. Your survey opinion may be highly accurate because you are on the true boundary lines and the true corners (you hit the bull’s-eye), but this doesn’t stop the next surveyor coming along--who has confused precision for accuracy--from driving new irons in the ground based on precise measurements and proclaiming the survey to be accurate. And therein lies our problem. Our brother has sinned because he’s missed the mark. But seldom does a sinner want to hear he’s a sinner. What now? How do we get him to repent?

Until the hearts and minds of surveyors are changed and a real understanding of our duties and responsibilities is achieved, we will continue to “mistaken entirely the point to which [our] attention should have been directed. … Indeed the mischiefs that must follow would be simply incalculable, and the visitation of the surveyor might well be set down as a great public calamity.”[7] The point is, boundary surveying is not a measurement problem, it’s an evidentiary problem. Our precise measurements have led us away from the accurate path and have caused us to miss the mark. We must turn from our sinful ways, my friends, before it’s too late.


1. “The Old Testament has a rich vocabulary for sin. Chata means ‘to miss the mark,’ as does the Greek hamartia.” Holman Bible Dictionary on the definition of sin.

2. Standards of Practice for Surveying in the State of Alabama (SOP), Effective May 7, 2002, Alabama Society of Professional Land Surveyors.

3. SOP, Rule 1.03, para.17.

4. 2005 Minimum Standard Detail Requirements for ALTA/ACSM Land Title Survey, American Land Title Association and the National Society of Professional Land Surveyors, at Page 6.

5. Accuracy versus Precision: Wikipedia.

6. Andrews v. Barton, 974 So.2d 1144, 1147 (Fla.App.2008).

7. Diehl v. Zanger, 39 Mich. 601, 605 (Mich.1878).

For a more in-depth study of the legal principles that affect our everyday practice, subscribe to “The Lucas Letter” at www.jnlucaspls.com/TheLucasLetter.html.

Neither the author nor POB intend this column to be a source of legal advice for surveyors or their clients. The law changes and differs in important respects for different jurisdictions. If you have a specific legal problem, the best source of advice is an attorney admitted to the bar in your jurisdiction.

This column is a forum for analysis and discussion of closed court cases. Facts and information cited are limited to what is contained in the published legal documents. It is not POB nor the author’s intent to re-try cases that have already been resolved and closed by the court system.