All posts by Charles D. Ghilani
Surveying Statistics
The t Distribution, Part 2 In the previous article (July 2015), I introduce the concept of sampling distributions and the need to use these distributions to analyze small samples of data. In surveying, observing small samples is typical where angles are often observed only two or four times, and repeated distance observations simply means pushing...
Surveying Statistics
The t Distribution, Part 1 In my previous article I discuss the normal distribution and how its properties can be used to isolate blunders in observations. Recall that the normal distribution is based on an infinite number of observations. However, in practice we never collect a population of data but rather a small sample from...
Surveying Statistics
Part 2: The Normal Distribution Part 1 of this series appeared in the May 2015 issue. Errors in observations can be classified as systematic or random. Systematic errors follow physical laws and can be mathematically corrected or removed by following proper field procedures with instruments. For example, the expansion or contraction of a steel tape...
The Normal Distribution, Part 1
Errors in observations can be classified as systematic or random. Systematic errors are errors that follow physical laws and can be mathematically corrected or removed by following proper field procedures with instruments. For example, the expansion or contraction of a steel tape caused by temperatures that differ from the tape’s standard temperature is a systematic...
I Don’t Need No Stinkin’ Statistics
Surveying Statistics, Part 1 Do you perform GNSS surveys? Do you use OPUS or perform RTK surveys simply because you don’t understand your software’s output? Do you always use the compass-rule adjustment for traverse data simply because that’s the way you have always done it? Do you ever have a situation where you know something...
Transformation of Observations, Part 4
Single Project Factor Here concludes a four-part series of articles about transformation of observations, spanning from September and December 2014 to March 2015. Part 1 covers how to transform surface observations into a geocentric coordinate system so that they can be compared to GNSS baseline vectors. Part 2 is about how the creation of a...
