mutestim | R Documentation |
Estimates mean number of mutations, mutation probability, and fitness parameter, with different methods, under different models. Returns the estimated means and standard deviations for each parameter.
mutestim(mc, fn = NULL, mfn = NULL, cvfn = NULL,
fitness = NULL, death = 0., plateff = 1.,
model = c("LD", "H", "I"), muinf = +Inf,
method = c("ML", "GF", "P0"),
winsor = 2000)
mc |
a (non-empty) numeric vector of mutants counts. |
fn |
an optional (non-empty) numeric vector with same length as |
mfn |
mean final number of cells. Ignored if |
cvfn |
coefficient of variation of final number of cells. Ignored if |
fitness |
fitness parameter: ratio of growth rates of normal and mutant cells. If |
death |
death probability. Must be smaller than 0.5. By default 0. |
plateff |
plating efficiency parameter. Must be non-larger than 1. By default 1. Available for |
model |
statistical lifetime model. Must be one of "LD" (default) for Luria-Delbrück model (exponential lifetimes), "H" for Haldane model (constant lifetimes), or "I" for Inhomogeneous model |
muinf |
parameter used only if |
method |
estimation method as a character string: one of |
winsor |
winsorization parameter: positive integer. Only used when |
Method ML
is the classic maximum likelihood estimation method. The maximum is computed with a BFGS (bounded) algorithm.
Method P0
uses the number of null values in the sample, therefore it can be applied only if there is at least one zero in mc
.
The estimate of the fitness is computed by maximum likelihood.
Method GF
uses the empirical generating function of mc
.
Since this method is the fastest, "GF"
is used to initialize the values of the estimates for methods "ML"
and "P0"
(if the fitness is estimated).
If fn
, mfn
or cvfn
is non-empty, then the mutation probability is estimated instead of the mean number of mutations.
If fn
is non-empty and method
is P0
or GF
, then mfn
and cvfn
are computed from fn
, and the estimate of
of the mutation probability is deduced from the estimate of the mean number of mutations.
If fn
is non-empty and method
is ML
, the estimate of the mutation probability is directly computed.
muinf
corresponds to the cumulative division rate on the interval [0 ; +Inf).
If model
is I
, muinf
has to be finite, else model
is set to "LD"
The winsorization parameter winsor
is used as a threshold for values in mc
when maximum likelihood estimates are computed.
A list containing the following components:
mutations |
mean number of mutations |
sd.mutations |
estimated standard deviation on mean number of mutations |
mutprob |
mutation probability (if |
sd.mutprob |
estimated standard deviation on mutation probability |
fitness |
estimated fitness (if argument |
sd.fitness |
estimated standard deviation on fitness |
A. Mazoyer: Fluctuation analysis on mutation models with birth-date dependence. Math. Biosci 303(9): 83-100 (2018)
B. Ycart and N. Veziris: Unbiased estimates of mutation rates under fluctuating final counts. PLoS one 9(7) e101434 (2014)
B. Ycart: Fluctuation analysis with cell deaths. J. Applied Probab. Statist, 9(1):12-28 (2014)
B. Ycart: Fluctuation analysis: can estimates be trusted? One PLoS one 8(12) e80958 (2013)
A. Hamon and B. Ycart: Statistics for the Luria-Delbrück distribution. Elect. J. Statist., 6:1251-1272 (2012)
rflan, flan.test
.
# realistic random sample of size 100: mutation probability 1e-9,
# mean final number 1e9, coefficient of variation on final numbers 0.3,
# fitness 0.9, lognormal lifetimes, 5% mutant deaths, plating efficiency 80%
x <- rflan(100, mutprob = 1e-9, mfn = 1e9, cvfn = 0.3, fitness = 0.9, death = 0.05, plateff = 0.8)
# maximum likelihood estimates with mean final number
meanfn <- mutestim(x$mc, mfn = 1e9)
# maximum likelihood estimates with final numbers
withfn <- mutestim(x$mc, x$fn)
# change model
Hmodel <- mutestim(x$mc, x$fn, model = "H")
# faster methods
GFmethod <- mutestim(x$mc, x$fn, method = "GF")
P0method <- mutestim(x$mc, x$fn, method = "P0")
# take deaths into account
withdeaths <- mutestim(x$mc, x$fn, death = 0.05, method = "GF")
# with plateff
withpef <- mutestim(x$mc, x$fn, death = 0.05, plateff = 0.8, method = "GF")
# compare results
rbind(meanfn, withfn, Hmodel, GFmethod, P0method, withdeaths, withpef)
# extreme example
x <- rflan(1000, mutations = 50, fitness = 0.5, dist = "exp")$mc
summary(x)
mutestim(x, method = "GF")
mutestim(x)
mutestim(x, winsor = 5000)
## Not run:
# None null count in the sample: P0 can not be used.
mutestim(x, method = "P0")
## End(Not run)
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