*! version 1.2.4 15dec2022

Title

agree -- Agreement: Passing-Bablok & Bland-Altman methods

Syntax

agree varnameY varnameX [if] [in] [, options]

ba calculate Bland-Altman comparison of two measurements methods; the default

pb calculate Passing-Bablok estimation of regression line

level(#) confidence level (%); default is level(95)

title(string) title for the graphics

nst(string) name of the study (label); if provided, it is also used as the subtitle for the graphics

Bland-Altman method
pct compute percentage values and graphic

line show regression line on Bland-Altman graphics

Passing-Bablok method
ci show confidence intervals on Passing-Bablok graphic

list list input data; the report include X-Y changes

id(varname) name of variable with identifier of cases for the list; default is _n

by is allowed; see [D] by.

Description

Passing-Bablok and Bland-Altman methods of agreement. The command needs the names of the numeric variables
with method X (reference) and method Y.

For the Passing-Bablok method of agreement, the CUSUM test for deviation from linearity is computed with
critical values obtained from the Kolmogorov-Smirnov test: 1.94947 (alpha=0.001); 1.62762 (alpha=0.01);
1.51743 (alpha=0.02); 1.35810 (alpha=0.05); 1.22385 (alpha=0.10); 1.13795 (alpha=0.15) and 1.07275 (alpha=0.20).

You can click here to pop up a dialog or type db agree.

Execute net from http://metodo.uab.cat/stata for install.

It is important to keep the commands updated. Execute adoupdate agree, update to update the agree command.

Execute adoupdate, update to update all the user-written commands.

This command uses the tabstat, summarize, swilk, sktest and spearman Stata commands.

If you find any bugs or want to suggest any improvements, please send an e-mail to: leam@uab.cat.

Examples

. use http://metodo.uab.cat/stata/agree_data.dta

. agree Instrumental Manual

. agree Instrumental Manual, ba pct line nst(Study name)

. agree Instrumental Manual, pb ci list id(Especimen)

Stored results

The command stores the following in r():

Scalars

r(N) valid number of cases (listwise)

r(level) confidence level of confidence intervals

r(lin) Lin's concordance correlation coeff. of absolute agreement

Passing-Bablok regression line

r(a) A

r(a_lb) lower bound of A confidence interval

r(a_ub) upper bound of A confidence interval

r(b) B

r(b_lb) lower bound of B confidence interval

r(b_ub) upper bound of B confidence interval

Bland-Altman Interval of Agreement

r(mean) Y-X: Bias Absolute values

r(mean_se) Y-X: Bias std. error Absolute values

r(LoA_lb) lower bound of LoA Absolute values

r(LoA_ub) upper bound of LoA Absolute values

r(LoA_se) std. error of LoA Absolute values

r(mean_pct) Y-X: Bias Percentage values

r(mean_se_pct) Y-X: Bias std. error Percentage values

r(LoA_lb_pct) lower bound of LoA Percentage values

r(LoA_ub_pct) upper bound of LoA Percentage values

r(LoA_se_pct) std. error of LoA Percentage values

r(rho) Spearman correlation between (Y-X) and (X+Y)/2

r(p_rho) significance of Spearman correlation

r(W) Shapiro-Wilk Tests of Normality

r(p_W) significance of Shapiro-Wilk Tests of Normality

r(sk) Skewness Tests of Normality

r(p_sk) significance of Skewness Tests of Normality

r(ku) Kurtosis-3 Tests of Normality

r(p_ku) significance of Kurtosis-3 Tests of Normality

r(chi2) Skewness & Kurtosis Tests of Normality

r(p_chi2) significance of Skewness & Kurtosis Tests of Normality

Macros

r(cusum) Passing-Bablok CUSUM Test for deviation from linearity

Matrices

r(Stats) Passing-Bablok statistics

Version

Version 1.2.4 -- 15 December 2022

Authors

JM.Doménech

Programmer: R.Sesma

Laboratori d'Estadística Aplicada

Universitat Autònoma de Barcelona

leam@uab.cat

Vancouver reference

Doménech JM. Passing-Bablok & Bland-Altman methods: User-written command agree for Stata [computer program].

V1.2.4. Bellaterra: Universitat Autònoma de Barcelona; 2022.

Available executing from Stata: net from http://metodo.uab.cat/stata

References

Bland M, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet. 1986;1:307-10.

Bland M, Altman DG. Comparing two methods of clinical measurement: a personal history. Int J Epidemiol. 1995;24 (Suppl. 1):S7-S14.

Doménech JM. Fundamentos de Diseño y Estadística. UD 14. Medida del cambio: Análisis de diseños con medidas
intrasujeto. 20ª ed. Barcelona: Signo; 2019.

Giavarina D. Understanding Bland Altman analysis. Biochem Med (Zagreb). 2015;25(2):141-51.

Lin LI. Concordance Correlation Coefficient to Evaluate Reproducibility. Biometrics. 1989;45:255-68.

Lin LI. Assay Validation Using the Concordance Correlation Coefficient. Biometrics. 1992;48:599-604.

Passing H, Bablok W. Application of statistical procedures in analytical instrument testing. J Automat
Chem. 1985;7(2):74-9.

Passing H, Bablok W. A new biometrical procedure for testing the equality of measurements from two different
analytical methods. Application of linear regression procedures for method comparison studies in clinical
chemistry. Part I. J Clin Chem Clin Biochem. 1983;21:709-20.

Passing H, Bablok W. Comparison of several regression procedures for method comparison studies and determination
of sample size. Application of linear regression procedures for method comparison studies in clinical
chemistry. Part II. J Clin Chem Clin Biochem. 1984;22:431-45.

Bablok W, Passing H, Bender R, Schneider B. A general regression procedure for method transformation. Application
of linear regression procedures for method comparison studies in clinical chemistry. Part III. J Clin
Chem Clin Biochem. 1988;26:783-90.