Method for detecting artifacts in data

A method for identifying artifacts in optical measurements conducted for the purpose of determination of concentration of an analyte in a tissue, or value of a physiological parameter, or a combination of the forgoing, the method comprising the steps of:

• (a) providing an apparatus for measuring at least one optical property of the tissue;
• (b) introducing electromagnetic radiation at at least one wavelength into the tissue by means of the apparatus;
• (c) collecting optical data from the tissue over a selected period of time;
• (d) introducing the collected data into an algorithm to identify an artifact in the optical data, the artifact resulting from movement of the probe or the tissue during a brief period of time;
• and
• (e) determining whether an artifact has appeared in the optical data,
• wherein the algorithm utilizes equations for calculating a set of values from the optical data, which optical data comprise a plurality of data points, the equations comprising:
• S(i)=[1−P]·S(i−1)+P·[X(i)−X(i−1)] (1)
• A(i)=[1−P]·[A(i−1)+S(i)]+P·X(i) (2)
• D(i)=|X(i)−A(i)| (3)
• Where:
• N=effective quantity of data points in the moving average for the algorithm (N=value greater than 1, as specified by user)
• Dc=artifact threshold value for D(i) (Dc=value greater than 0, as specified by user)
• P=algorithm constant (P=2/[N+1])
• i=current data point number (i is greater than 1)
• X(i)=value of the current data point
• X(i−1)=value of the previous data point
• X(1)=value of the first data point
• S(i)=value of slope parameter at the current data point
• S(i−1)=value of slope parameter at the previous data point
• S(1)=value of slope parameter at the first data point (S(1)=0)
• A(i) =value of moving average at the current data point
• A(i−1)=value of moving average at the previous data point A(1)=value of moving average at the first data point (A(1)=X(1))
• D(i)=absolute difference between X(i) and A(i) at the current data point.