Online Retraining

Select a model.
Select a previously trained model.
Train a new SVM for Sleep Staging or to predict Sleep Disordered Breathing. While training is in progress, you may navigate away from the page or close your browser. Trained models can be saved for later use in the Analysis section of the platform. Select an existing model to continue training (a warm start, with or without new data), or configure and train a new model.
Model configuration.
Configuration

Select between training a Support Vector Classifier (SVC), a binary classifier to predict whether the AHI of a child is at least 5 or to classify recording as Sleep or Wake, or a Support Vector Regressor (SVR) to produce a point estimate of the AHI. Select a Linear, Gaussian, or Polynomial kernel. The Linear kernel allows for substantially better model interpretability, while the Gaussian kernel is more flexible and may capture non-linearities at the expense of interpretability. Polynomial kernels offer a balance in complexity and the degree of non-linearity is configurable.
Model Information

Feature Selection
Feature Description
Desats Continuous drops in the O2 saturation of at least 3%.
Desat Depth Cumulative percentage drop in the O2 saturation during desaturations.
Desat Duration Cumulative duration of desaturations to resaturation.
Desat Area Cumulative area of desaturations to resaturation.
Baseline 90-second averaged O2 saturation baseline that does not include desaturations.
OSA Band Power Median Spectral component that encompasses half the power within the power spectral density of the OSA Band (0.01-0.035Hz) as computed using a Chirp-Z Transform.
OSA Band Power Mean First statistical moment of the power spectral density of the OSA Band.
OSA Band Power Variance Second statistical moment of the power spectral density of the OSA Band
OSA Band Power Skewness Third statistical moment of the power spectral density of the OSA Band.
OSA Band Power Kurtosis Fourth statistical moment of power spectral density of the OSA Band.
OSA Band Power Maximum Spectral component within the power spectral density of the OSA Band with the highest power.
OSA Band Power Max Ratio Spectral component within the power spectral density of the OSA Band with the highest power, relative to the highest power observed in the complete spectrum.
OSA Band Power Sum Sum of spectral component within the power spectral density of the OSA Band.
OSA Band Power Sum Ratio Sum of spectral component within the power spectral density of the OSA Band, relative to the sum of the power observed in the complete spectrum.
Sats Mean First statistical moment of the O2 saturation.
Sats Variance Second statistical moment of the O2 saturation.
Sats Skewness Third statistical moment of the O2 saturation.
Sats Kurtosis Fourth statistical moment of the O2 saturation.
Sats CTM1 Central Tendency Measure of the O2 saturation where the radius equals 1. A measure of variability in the O2 saturation.
Sats CTM3 Central Tendency Measure of the O2 saturation where the radius equals 3. A measure of variability in the O2 saturation.
Sats CTM6 Central Tendency Measure of the O2 saturation where the radius equals 6. A measure of variability in the O2 saturation.
Sats Complexity Lempel-Ziv Complexity of the O2 saturation. A measure of repeating sequences in the O2 saturation.
Sats RMSSD Root mean square of successive differences in the O2 saturation. RMSSD is commonly used as a measure of heart rate variability.
Sats Entropy Shannon entropy of the O2 saturation. A measure of regularity.
Sats Sample Entropy Sample entropy of the O2 saturation where the template length equals 2, and the tolerance equals the product of 0.2 and the standard deviation of the O2 saturation. A measure of regularity.
Sats Power Median Spectral component that encompasses half the power within the power spectral density of the O2 saturation as computed using a Chirp-Z Transform.
Sats Power Mean First statistical moment of the power spectral density of the O2 saturation.
Sats Power Variance Second statistical moment of the power spectral density of the O2 saturation.
Sats Power Skewness Third statistical moment of the power spectral density of the O2 saturation.
Sats Power Kurtosis Fourth statistical moment of the power spectral density of the O2 saturation..
Sats Power Maximum Spectral component within the power spectral density of the O2 saturation with the highest power.
Sats Power Sum Sum of spectral component within the power spectral density of the O2 saturation.
Sats DFA3 Detrended fluctuation analysis of the O2 saturation where the window is of size 3. A measurement of self-affinity in the O2 saturation.
Sats DFA7 Detrended fluctuation analysis of the O2 saturation where the window is of size 7. A measurement of self-affinity in the O2 saturation.
Sats DFA Trend Minimum Minimum trend observed during DFA analysis of the O2 saturation.
Sats DFA Trend Mean Mean trend in DFA analysis of the O2 saturation.
Sats DFA Trend Maximum Maximum trend in DFA analysis of the O2 saturation.
Sats AutoCorr 1 First-order autocorrelation of the O2 saturation. Measures the correlation of the O2 saturation with a delayed copy of itself.
Sats AutoCorr 2 Second-order autocorrelation of the O2 saturation. Measures the correlation of the O2 saturation with a delayed copy of itself.
Sats AutoCorr 3 Third-order autocorrelation of the O2 saturation. Measures the correlation of the O2 saturation with a delayed copy of itself.
Sats AutoCorr 4 Fourth-order autocorrelation of the O2 saturation. Measures the correlation of the O2 saturation with a delayed copy of itself.
Pulse Rate Mean First statistical moment of the pulse rate.
Pulse Rate Variance Second statistical moment of the pulse rate.
Pulse Rate Skewness Third statistical moment of the pulse rate.
Pulse Rate Kurtosis Fourth statistical moment of the pulse rate.
Pulse Rate CTM1 Central Tendency Measure of the pulse rate where the radius equals 1. A measure of variability in the pulse rate.
Pulse Rate CTM3 Central Tendency Measure of the pulse rate where the radius equals 3. A measure of variability in the pulse rate.
Pulse Rate CTM6 Central Tendency Measure of the pulse rate where the radius equals 6. A measure of variability in the pulse rate.
Pulse Rate Complexity Lempel-Ziv Complexity of the pulse rate. A measure of repeating sequences in the pulse rate.
Pulse Rate RMSSD Root mean square of successive differences in the pulse rate. RMSSD is commonly used as a measure of heart rate variability.
Pulse Rate Entropy Shannon entropy of the pulse rate. A measure of regularity.
Pulse Rate Sample Entropy Sample entropy of the pulse rate where the template length equals 2, and the tolerance equals the product of 0.2 and the standard deviation of the O2 saturation. A measure of regularity.
Pulse Rate Power Median Spectral component that encompasses half the power within the power spectral density of the pulse rate as computed using a Chirp-Z Transform.
Pulse Rate Power Mean First statistical moment of the power spectral density of the pulse rate.
Pulse Rate Power Variance Second statistical moment of the power spectral density of the pulse rate.
Pulse Rate Power Skewness Third statistical moment of the power spectral density of the pulse rate.
Pulse Rate Power Kurtosis Fourth statistical moment of the power spectral density of the pulse rate.
Pulse Rate Power Maximum Spectral component within the power spectral density of the pulse rate with the highest power.
Pulse Rate Power Sum Sum of spectral component within the power spectral density of the pulse rate.
Pulse Rate DFA3 Detrended fluctuation analysis of the pulse rate where the window is of size 3. A measurement of self-affinity in the pulse rate.
Pulse Rate DFA7 Detrended fluctuation analysis of the pulse rate where the window is of size 7. A measurement of self-affinity in the pulse rate.
Pulse Rate DFA Trend Minimum Minimum trend observed during DFA analysis of the pulse rate.
Pulse Rate DFA Trend Mean Mean trend in DFA analysis of the pulse rate.
Pulse Rate DFA Trend Maximum Maximum trend in DFA analysis of the pulse rate.
Pulse Rate AutoCorr 1 First-order autocorrelation of the pulse rate. Measures the correlation of the pulse rate with a delayed copy of itself.
Pulse Rate AutoCorr 2 Second-order autocorrelation of the pulse rate. Measures the correlation of the pulse rate with a delayed copy of itself.
Pulse Rate AutoCorr 3 Third-order autocorrelation of the pulse rate. Measures the correlation of the pulse rate with a delayed copy of itself.
Pulse Rate AutoCorr 4 Fourth-order autocorrelation of the pulse rate. Measures the correlation of the pulse rate with a delayed copy of itself.
VAR Sats (-1) -> Pulse Rate Vector Autoregression beta-coefficient for the lagged O2 saturation (-1) as a predictor of pulse rate, using a multivariable ordinary least squares regression model.
VAR Sats (-2) -> Pulse Rate Vector Autoregression beta-coefficient for the lagged O2 saturation (-2) as a predictor of pulse rate, using a multivariable ordinary least squares regression model.
VAR Sats (-3) -> Pulse Rate Vector Autoregression beta-coefficient for the lagged O2 saturation (-3) as a predictor of pulse rate, using a multivariable ordinary least squares regression model.
VAR Sats (-4) -> Pulse Rate Vector Autoregression beta-coefficient for the lagged O2 saturation (-4) as a predictor of pulse rate, using a multivariable ordinary least squares regression model.
VAR Pulse Rate (-1) -> Sats Vector Autoregression beta-coefficient for the lagged pulse rate (-1) as a predictor of O2 saturation, using a multivariable ordinary least squares regression model.
VAR Pulse Rate (-2) -> Sats Vector Autoregression beta-coefficient for the lagged pulse rate (-2) as a predictor of O2 saturation, using a multivariable ordinary least squares regression model.
VAR Pulse Rate (-3) -> Sats Vector Autoregression beta-coefficient for the lagged pulse rate (-3) as a predictor of O2 saturation, using a multivariable ordinary least squares regression model.
VAR Pulse Rate (-4) -> Sats Vector Autoregression beta-coefficient for the lagged pulse rate (-4) as a predictor of O2 saturation, using a multivariable ordinary least squares regression model.
Desat Depth (%/hr) Cumulative percentage drop in the O2 saturation, during desaturations, from a 90-second averaged baseline.
CT90 (samples/hr) Cumulative time below 90% O2 saturation per hour.
CT95 (samples/hr) Cumulative time below 95% O2 saturation per hour.
ODI3 Desaturations of at least 3% from a 90-second averaged baseline.
D85/hr Number of desaturations below 85% O2 saturation per hour.
D90/hr Number of desaturations below 90% O2 saturation per hour.
Desats/hr (any 3%) Total desaturations of at least 3% per hour.
Add additional training data.
Additional training data may be optionally added to the default training set. If this is a warm start of a previously trained model, these data will be included in the retraining process.
Training dashboard.
Bayesian Optimisation

C: The regularisation parameter that balances minimising training error (high C) and model generalisability (low C).Gamma: Balances decision boundary complexity (high Gamma) and simplicity (low Gamma). Coef0: A constant offset that balances complexity (low Coef0) and simplicity (high Coef0).Epsilon: Width of the epsilon-insensitive tube. Balances precision (low Epsilon) and generalisability (high Epsilon).
SVM Training Progress

Training in progress. You may use the analysis functionality or close your browser.

Finished

Parameters: C=25.663, Gamma=0.01, Coef0=1.171, Epsilon=3.01
Bayesian Optimisation
Gaussian Process Surface
Validation Error

Bayesian Optimisation of hyperparameters across iterations.

051015
Expected Improvement
Predicted Mean Absolute Error (AHI)
Bayesian Optimisation is used to search the hyperparameter ranges provided. This process attempts to balance exploration and exploitation to select the optimal values for the trained model. Gaussian Process Regression (GPR) and the Expected Improvement acquisition function are used. For each set of hyperparameters, SVMs are trained using Sequential Minimal Optimisation (SMO) with several heuristics to ensure timely model convergence (Platt, 1998; Fan et al., 2005). K-fold cross-validation is used to produce a validation error which is input into the GPR that underpins the Bayesian Optimisation. The most optimal hyperparameters, as determined by the optimisation process, are then used to train the final model. SVMs are calibrated using cross-validation data when training is complete so that predictions are accompanied by estimates of uncertainty. A trained Ridge Logistic Regression model is embedded within SVC to produce a probability point-estimate, and a Laplace distribution is computed for SVR to produce confidence intervals that accompany the AHI point-estimate. Continuing the training of a previously trained model (i.e., a warm start) may significantly reduce training time. This process may be leveraged to quickly search for more performant hyper-parameter combinations, or to quickly redeploy a model with updated training data. You may save the trained model when training is complete. Saved models are accessible through the analysis feature of the platform.