The analysis of threshold effect using Empower Stats software / 中华流行病学杂志

ABSTRACT

In many studies about biomedical research factors influence on the outcome variable,it has no influence or has a positive effect within a certain range.Exceeding a certain threshold value,the size of the effect and/or orientation will change,which called threshold effect.Whether there are threshold effects in the analysis of factors (x) on the outcome variable (y),it can be observed through a smooth curve fitting to see whether there is a piecewise linear relationship.And then using segmented regression model,LRT test and Bootstrap resampling method to analyze the threshold effect.Empower Stats software developed by American X & Y Solutions Inc has a threshold effect analysis module.You can input the threshold value at a given threshold segmentation simulated data.You may not input the threshold,but determined the optimal threshold analog data by the software automatically,and calculated the threshold confidence intervals.