cellsurvLQdiff: Comparison of two linear-quadratic cell survival curves

Description Usage Arguments Details Value Author(s) See Also Examples

View source: R/cellsurvLQdiff.R

Description

The function does an ANOVA test for overall comparison of the parameters alpha and beta of two linear-quadratic cell survival curves. The parameters are fitted simultaneously to the data with this function, i.e. no other function is necessary to derive the fits.

Usage

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cellsurvLQdiff(X, curvevar, method="ml", PEmethod="fit")

Arguments

X

A data frame which contains columns Exp, dose, ncells, ncolonies and a further column containing two different values (character strings), which identify the two curves. Moreover, if there is no 0-value in the dose-column, X has to contain a column pe for plating efficiencies.

curvevar

Character string, which has to be one of the column names of the data frame X, that contains the two different values (character strings that distinguishes between the two curves).

method

Determines the method used for the fit. "ml" is for maximum-likelihood, "ls" for least-squares. "franken" performs weigthed least-squares with weights as described in Franken et al. (2006).

PEmethod

Controls the value of the plating efficiencies, i.e. the colony counts for untreated cells. "fit" calculates fitted plating efficiencies as model parameters, "fix" uses fixed ones calculated from the observed zero dose data or from a column named pe in X.

Details

In the data frame X, Exp identifies the experimental replicates and may be numeric or non-numeric. method="ml" for maximum-likelihood uses R function glm with family "quasipoisson" and link function "log". method="ls" uses R function lm.

Value

The function returns an object of class cellsurvLQdiff containing three elements, fit1, fit2 and anv. fit1 and fit2 are objects of class glm when method="ml" or of class lm when method="ls". fit1 has parameters alpha and beta fitted in common for both cell survival curves. fit2 has parameters alpha and beta fitted differently for both curves. anv is of class anova and contains the F-test. Test results are printed, however, the full result inlcuding curve parameters is returned invisibly, i.e. the function has to be used with print or assigned to a variable, say for e.g. fitcomp as in the example below.

Author(s)

Herbert Braselmann

See Also

glm and family with references for generalized linear modelling. anova, cellsurvLQfit.

Examples

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datatab<- read.table(system.file("doc", "expl1_cellsurvcurves.txt", package="CFAssay"), header=TRUE, sep="\t")
names(datatab) #contains a column "cline"
table(datatab$cline)
fitcomp<- cellsurvLQdiff(datatab, curvevar="cline") #using default options
print(fitcomp)
plot(cellsurvLQfit(subset(datatab, cline=="okf6TERT1")), col=1)
plot(cellsurvLQfit(subset(datatab, cline=="cal33")), col=2, add=TRUE)
legend(0, 0.02, c("okf6TERT1", "cal33"), text.col=1:2)
#using different options:
print(cellsurvLQdiff(datatab, curvevar="cline", method="ls"))
print(cellsurvLQdiff(datatab, curvevar="cline", PEmethod="fix"))
print(cellsurvLQdiff(datatab, curvevar="cline", method="ls", PEmethod="fix"))
print(cellsurvLQdiff(datatab, curvevar="cline", method="franken"))

Example output

[1] "cline"     "Exp"       "dose"      "ncells"    "ncolonies"

    cal33 okf6TERT1 
       24        48 
*** Overall comparison for two linear-quadratic cell survival curves *** 
Compared curves: cal33 okf6TERT1 
method: ml 
PEmethod: fit 

Test used: F-test 
            F   Pr(>F)   
values 7.3509 0.001463 **
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
Use 'print' to see detailed results 

Overall comparison test for coefficients alpha and beta of LQ-models 
==================================================================== 
method = ml 
PEmethod = fit 

12 PEs fitted as intercepts. To look at, use simple R print function. 
Null hypothesis (Model 1): one set of shape parameters alpha and beta for all data 
---------------------------------------------------------------------------------- 
         Estimate  Std. Error   t value     Pr(>|t|)
alpha -0.39893900 0.047865098 -8.334653 1.687495e-11
beta  -0.03434671 0.007828292 -4.387510 4.906364e-05

Goodness-of-fit values 
	Residual Deviance: 317.2604 
	Total sum of squared weighted residuals rsswTot: 319.7611 
	Residual Degrees of Freedom: 58 
	Dispersion parameter: 5.513123 

Alternative hypothesis (Model 2): two sets of shape parameters alpha and beta 
----------------------------------------------------------------------------- 
                         Estimate  Std. Error   t value     Pr(>|t|)
alpha:curvescal33     -0.26831918 0.062588637 -4.287027 7.206618e-05
alpha:curvesokf6TERT1 -0.51937898 0.059669207 -8.704305 5.439622e-12
beta:curvescal33      -0.04892355 0.010058934 -4.863691 9.739225e-06
beta:curvesokf6TERT1  -0.02102614 0.009918948 -2.119795 3.846873e-02

Goodness-of-fit values 
	Residual Deviance: 251.804 
	Total sum of squared weighted residuals rsswTot: 249.3271 
	Residual Degrees of Freedom: 56 
	Dispersion parameter: 4.452269 

Analysis of Variance Table and F-test
Model 2 versus Model 1
  Resid. Df Resid. Dev Df Deviance      F   Pr(>F)   
1        58     317.26                               
2        56     251.80  2   65.456 7.3509 0.001463 **
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
method = ml 
PEmethod = fit 
       dose       dose2 
-0.51937898 -0.02102614 
Use 'print' to see detailed results 

method = ml 
PEmethod = fit 
       dose       dose2 
-0.26831918 -0.04892355 
Use 'print' to see detailed results 

*** Overall comparison for two linear-quadratic cell survival curves *** 
Compared curves: cal33 okf6TERT1 
method: ls 
PEmethod: fit 

Test used: F-test 
            F    Pr(>F)    
values 8.5624 0.0005695 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
Use 'print' to see detailed results 

Overall comparison test for coefficients alpha and beta of LQ-models 
==================================================================== 
method = ls 
PEmethod = fit 

12 PEs fitted as intercepts. To look at, use simple R print function. 
Null hypothesis (Model 1): one set of shape parameters alpha and beta for all data 
---------------------------------------------------------------------------------- 
         Estimate  Std. Error   t value     Pr(>|t|)
alpha -0.44210271 0.058993395 -7.494105 4.330475e-10
beta  -0.03097808 0.009374666 -3.304446 1.634899e-03


Goodness-of-fit values 
	Total sum of squared residuals rssTot: 5.138071 
	Residual Degrees of Freedom: 58 
	Multiple R-squared: 0.95907 

Alternative hypothesis (Model 2): two sets of shape parameters alpha and beta 
----------------------------------------------------------------------------- 
                         Estimate Std. Error   t value     Pr(>|t|)
alpha:curvescal33     -0.25601286 0.09100092 -2.813300 6.751349e-03
alpha:curvesokf6TERT1 -0.53514763 0.06434737 -8.316543 2.336628e-11
beta:curvescal33      -0.04744575 0.01446100 -3.280946 1.783720e-03
beta:curvesokf6TERT1  -0.02274424 0.01022547 -2.224274 3.017867e-02


Goodness-of-fit values 
	Total sum of squared residuals rssTot: 3.934809 
	Residual Degrees of Freedom: 56 
	Multiple R-squared: 0.9686552 

Analysis of Variance Table and F-test
Model 2 versus Model 1
  Res.Df    RSS Df Sum of Sq      F    Pr(>F)    
1     58 5.1381                                  
2     56 3.9348  2    1.2033 8.5624 0.0005695 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
*** Overall comparison for two linear-quadratic cell survival curves *** 
Compared curves: cal33 okf6TERT1 
method: ml 
PEmethod: fix 

Test used: F-test 
            F   Pr(>F)    
values 19.637 3.45e-07 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
Use 'print' to see detailed results 

Overall comparison test for coefficients alpha and beta of LQ-models 
==================================================================== 
method = ml 
PEmethod = fix 

Null hypothesis (Model 1): one set of shape parameters alpha and beta for all data 
---------------------------------------------------------------------------------- 
         Estimate  Std. Error   t value     Pr(>|t|)
alpha -0.36939379 0.048055945 -7.686745 2.054860e-10
beta  -0.03910804 0.009968124 -3.923310 2.339076e-04

Goodness-of-fit values 
	Residual Deviance: 897.6402 
	Total sum of squared weighted residuals rsswTot: 841.7324 
	Residual Degrees of Freedom: 58 
	Dispersion parameter: 14.51263 

Alternative hypothesis (Model 2): two sets of shape parameters alpha and beta 
----------------------------------------------------------------------------- 
                         Estimate Std. Error   t value     Pr(>|t|)
alpha:curvescal33     -0.22802046 0.05241601 -4.350207 5.815804e-05
alpha:curvesokf6TERT1 -0.51079080 0.05609421 -9.105946 1.216308e-12
beta:curvescal33      -0.05423143 0.01101630 -4.922835 7.891563e-06
beta:curvesokf6TERT1  -0.02274661 0.01150507 -1.977095 5.296198e-02

Goodness-of-fit values 
	Residual Deviance: 538.1011 
	Total sum of squared weighted residuals rsswTot: 512.6458 
	Residual Degrees of Freedom: 56 
	Dispersion parameter: 9.154389 

Analysis of Variance Table and F-test
Model 2 versus Model 1
  Resid. Df Resid. Dev Df Deviance      F   Pr(>F)    
1        58     897.64                                
2        56     538.10  2   359.54 19.637 3.45e-07 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
*** Overall comparison for two linear-quadratic cell survival curves *** 
Compared curves: cal33 okf6TERT1 
method: ls 
PEmethod: fix 

Test used: F-test 
            F    Pr(>F)    
values 15.038 5.924e-06 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
Use 'print' to see detailed results 

Overall comparison test for coefficients alpha and beta of LQ-models 
==================================================================== 
method = ls 
PEmethod = fix 

Null hypothesis (Model 1): one set of shape parameters alpha and beta for all data 
---------------------------------------------------------------------------------- 
         Estimate Std. Error   t value     Pr(>|t|)
alpha -0.42775991 0.06443191 -6.638945 1.181206e-08
beta  -0.03278904 0.01288638 -2.544472 1.362888e-02


Goodness-of-fit values 
	Total sum of squared residuals rssTot: 15.83755 
	Residual Degrees of Freedom: 58 
	Multiple R-squared: 0.984003 

Alternative hypothesis (Model 2): two sets of shape parameters alpha and beta 
----------------------------------------------------------------------------- 
                         Estimate Std. Error   t value     Pr(>|t|)
alpha:curvescal33     -0.22201908 0.09160853 -2.423564 1.862519e-02
alpha:curvesokf6TERT1 -0.53063032 0.06477701 -8.191646 3.744222e-11
beta:curvescal33      -0.05173789 0.01832171 -2.823858 6.560102e-03
beta:curvesokf6TERT1  -0.02331461 0.01295540 -1.799605 7.731114e-02


Goodness-of-fit values 
	Total sum of squared residuals rssTot: 10.30378 
	Residual Degrees of Freedom: 56 
	Multiple R-squared: 0.9895589 

Analysis of Variance Table and F-test
Model 2 versus Model 1
  Res.Df    RSS Df Sum of Sq      F    Pr(>F)    
1     58 15.838                                  
2     56 10.304  2    5.5338 15.038 5.924e-06 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
*** Overall comparison for two linear-quadratic cell survival curves *** 
Compared curves: cal33 okf6TERT1 
method: franken 
PEmethod: fix 

Test used: F-test 
            F    Pr(>F)    
values 16.948 1.756e-06 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
Use 'print' to see detailed results 

Overall comparison test for coefficients alpha and beta of LQ-models 
==================================================================== 
method = franken 
PEmethod = fix 

Null hypothesis (Model 1): one set of shape parameters alpha and beta for all data 
---------------------------------------------------------------------------------- 
         Estimate  Std. Error   t value     Pr(>|t|)
alpha -0.34268389 0.044434197 -7.712166 1.862428e-10
beta  -0.03917355 0.009218242 -4.249568 7.867653e-05

Goodness-of-fit values 
	Total sum of squared weighted residuals rsswTot: 767.0095 
	Residual Degrees of Freedom: 58 
	Multiple R-squared: 0.990357 

Alternative hypothesis (Model 2): two sets of shape parameters alpha and beta 
----------------------------------------------------------------------------- 
                         Estimate Std. Error   t value     Pr(>|t|)
alpha:curvescal33     -0.22859933 0.04836349 -4.726692 1.580129e-05
alpha:curvesokf6TERT1 -0.48879371 0.05293026 -9.234675 7.547585e-13
beta:curvescal33      -0.05214356 0.01011265 -5.156271 3.413201e-06
beta:curvesokf6TERT1  -0.02190780 0.01087920 -2.013733 4.885208e-02

Goodness-of-fit values 
	Total sum of squared weighted residuals rsswTot: 477.8013 
	Residual Degrees of Freedom: 56 
	Multiple R-squared: 0.9939996 

Analysis of Variance Table and F-test
Model 2 versus Model 1
  Res.Df    RSS Df Sum of Sq      F    Pr(>F)    
1     58 767.01                                  
2     56 477.80  2    289.21 16.948 1.756e-06 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

CFAssay documentation built on Nov. 8, 2020, 11:10 p.m.