A method of estimating a parameter of a process control loop, wherein the process control loop includes a valve controlled in accordance with an input command signal, the method comprising: measuring an output signal within the process control loop when the process control loop is connected on-line within a process control environment, wherein the input command signal is a pressure signal supplied to an actuator of the valve, and wherein the output signal is a position signal indicative of a position of the actuator of the valve; storing the measured output signal and the input command signal as a series of data points, each data point having a first component derived from the input command signal and a second component derived from the output signal; partitioning the stored series of data points into a plurality of non-overlapping data segments of equal size, each data segment corresponding to a particular range of travel of the actuator of the valve; characterized by further comprising: performing a statistical analysis on at least some of the plurality of data segments to generate a set of two or more segment-specific estimates of the parameter of the process control loop, wherein each one of the two or more segment specific parameters corresponds to a respective data segment of the plurality of data segments; storing a threshold value associated with the parameter; comparing each of the two or more segment specific parameters to the threshold value; generating a problem indication in response to detecting that a certain segment-specific estimate is above the threshold value; calculating an average of the set of segment-specific estimates; comparing each of the set of segment-specific estimates to the average of the set of segment-specific estimates; and generating a further problem indication in response to detecting that at least one of the set of segment-specific estimates differs from the average of the set of segment-specific estimates by more than a certain amount. measuring an output signal within the process control loop when the process control loop is connected on-line within a process control environment, wherein the input command signal is a pressure signal supplied to an actuator of the valve, and wherein the output signal is a position signal indicative of a position of the actuator of the valve; storing the measured output signal and the input command signal as a series of data points, each data point having a first component derived from the input command signal and a second component derived from the output signal; partitioning the stored series of data points into a plurality of non-overlapping data segments of equal size, each data segment corresponding to a particular range of travel of the actuator of the valve; characterized by further comprising: performing a statistical analysis on at least some of the plurality of data segments to generate a set of two or more segment-specific estimates of the parameter of the process control loop, wherein each one of the two or more segment specific parameters corresponds to a respective data segment of the plurality of data segments; storing a threshold value associated with the parameter; comparing each of the two or more segment specific parameters to the threshold value; generating a problem indication in response to detecting that a certain segment-specific estimate is above the threshold value; calculating an average of the set of segment-specific estimates; comparing each of the set of segment-specific estimates to the average of the set of segment-specific estimates; and generating a further problem indication in response to detecting that at least one of the set of segment-specific estimates differs from the average of the set of segment-specific estimates by more than a certain amount. performing a statistical analysis on at least some of the plurality of data segments to generate a set of two or more segment-specific estimates of the parameter of the process control loop, wherein each one of the two or more segment specific parameters corresponds to a respective data segment of the plurality of data segments; storing a threshold value associated with the parameter; comparing each of the two or more segment specific parameters to the threshold value; generating a problem indication in response to detecting that a certain segment-specific estimate is above the threshold value; calculating an average of the set of segment-specific estimates; comparing each of the set of segment-specific estimates to the average of the set of segment-specific estimates; and generating a further problem indication in response to detecting that at least one of the set of segment-specific estimates differs from the average of the set of segment-specific estimates by more than a certain amount.