Dear all, I am currently writing up my MA thesis in Applied Linguistics on Measures of Complexity, Accuracy and Fluency, from a Dynamic Systems View Perspective. We often use min-max diagrams to indicate whether there are periods of high or low variability, like this: "To identify periods with different degrees of variability within the variables, moving min-max diagrams were created, where the minimum and maximum values of 5 instances was taken, as the following example shows: min(t1...t5), min(t2...t6), min (t3...t7), etc. max(t1...t5), max(t2...t6), max (t3...t7), etc." Here is one of the resulting diagrams: <link removed for privacy reasons> --fuzzy As you can see, there are periods of high and low variability, but I want to know whether these changes are significant. Could I do something with surface change over time? Say, when the average surface of a min-max diagram over 5 t units decreases or increases by at least 50 percent for 5 subsequent t units, then there is a significant change? Or are there some traditional statistical measures to calculate this? I know of the way devised by Van Geert (1997) to use resampling and Monte Carlo analyses to find if the differences found in a set of data are significant, but that is only very rarely significant... I am not an expert on Math at all, so I hope you will have some ideas. Best, Wouter
Dear all, I am currently writing up my MA thesis in Applied Linguistics on Measures of Complexity, Accuracy and Fluency, from a Dynamic Systems View Perspective. We often use min-max diagrams to indicate whether there are periods of high or low variability, like this: "To identify periods with different degrees of variability within the variables, moving min-max diagrams were created, where the minimum and maximum values of 5 instances was taken, as the following example shows: min(t1...t5), min(t2...t6), min (t3...t7), etc. max(t1...t5), max(t2...t6), max (t3...t7), etc." Here is one of the resulting diagrams: <link removed for privacy reasons> --fuzzy As you can see, there are periods of high and low variability, but I want to know whether these changes are significant. Could I do something with surface change over time? Say, when the average surface of a min-max diagram over 5 t units decreases or increases by at least 50 percent for 5 subsequent t units, then there is a significant change? Or are there some traditional statistical measures to calculate this? I know of the way devised by Van Geert (1997) to use resampling and Monte Carlo analyses to find if the differences found in a set of data are significant, but that is only very rarely significant... I am not an expert on Math at all, so I hope you will have some ideas. Best, Wouter