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Table 3 Comparisons of eight different permanent approaches in the prediction of adjusted resin

From: A high-throughput quantification of resin and rubber contents in Parthenium argentatum using near-infrared (NIR) spectroscopy

Cross validation

DRY + IRR

DRY

IRR

\({\text{R}}_{\text{CV}}^{2}\)

RMSECV

RMSEC

RMSECV/RMSEC

F

 

\({\text{R}}_{\text{CV}}^{2}\)

RMSECV

RMSEC

RMSECV/RMSEC

F

 

\({\text{R}}_{\text{CV}}^{2}\)

RMSECV

RMSEC

RMSECV/RMSEC

F

 

No preprocessing

0.745

1.541

1.522

1.013

7

 

0.777

1.367

1.333

1.026

7

 

0.682

1.566

1.535

1.020

7

 

Smoothing

0.746

1.540

1.522

1.012

7

 

0.778

1.365

1.333

1.024

7

 

0.680

1.571

1.535

1.023

7

 

Smoothing + normalization

0.740

1.556

1.537

1.012

6

 

0.779

1.361

1.334

1.020

6

 

0.686

1.556

1.521

1.023

7

 

Smoothing + baseline + normalization

0.738

1.564

1.550

1.009

7

 

0.776

1.369

1.341

1.021

7

 

0.694

1.534

1.502

1.022

7

 

SNV

0.746

1.539

1.526

1.009

6

 

0.780

1.359

1.331

1.021

6

 

0.686

1.555

1.522

1.021

6

 

SNV + DT

0.747

1.536

1.517

1.013

7

 

0.788

1.334

1.295

1.030

7

 

0.685

1.558

1.523

1.023

6

 

SNV + DT + 1st derivative

0.746

1.539

1.518

1.014

5

 

0.776

1.371

1.355

1.012

3

 

0.691

1.543

1.528

1.009

3

 

SNV + DT + 2nd derivative

0.729

1.590

1.569

1.013

3

 

0.820

1.230

1.070

1.149

7

 

0.688

1.551

1.510

1.027

3

 

External validation

\({\text{R}}_{\text{P}}^{2}\)

RMSEP

RMSEC

RMSEP/RMSEC

F

RPD

\({\text{R}}_{\text{P}}^{2}\)

RMSEP

RMSEC

RMSEP/RMSEC

F

RPD

\({\text{R}}_{\text{P}}^{2}\)

RMSEP

RMSEC

RMSEP/RMSEC

F

RPD

SNV + DT + 2nd derivative

0.764

1.486

1.437

1.034

6

2.056

0.829

1.200

1.070

1.121

7

2.413

0.765

1.343

1.297

1.036

7

2.065

  1. Smoothing: median filter smoothing; Normalization: normalization by mean; Baseline: offset and linear baseline correction; SNV: standard normal variate; DT: de-trending, 2nd polynomial; Savitzky–Golay 1st derivative, 2nd polynomial, 23 smoothing points; Savitzky–Golay 2nd derivative, 2nd polynomial, 23 smoothing points
  2. R2, coefficient of determination; RMSECV, root mean squared error of cross validation; RMSEC, root mean squares error of calibration; RMSEP, root mean squared error of prediction; CV, cross validation; EV, external validation; F, number of factors (latent values) used in calibration; RPD, ratio of performance over prediction