ChangePointEstimator {MSstatsQC} | R Documentation

## A function to identify the time of a change in the mean or variability of a metric

### Description

A function to identify the time of a change in the mean or variability of a metric

### Usage

    ChangePointEstimator(data = NULL, peptide, L = 1, U = 5, metric,
      normalization = TRUE, ytitle = "Change Point Plot - mean",
      type = "mean", selectMean = NULL, selectSD = NULL)

### Arguments

`data` | comma-separated (.csv), metric file. It should contain a "Precursor" column and the metrics columns. It should also include "Annotations" for each observation.
`peptide` | the name of precursor of interest.
`L` | Lower bound of the guide set.
`U` | Upper bound of the guide set.
`metric` | the name of metric of interest.
`normalization` | TRUE metric is standardized and FALSE if not standardized.
`ytitle` | the y-axis title of the plot. Defaults to "Change Point Plot - mean". The x-axis title is by default "QCno-name of peptide"
`type` | the type of the control chart. Two values can be assigned, "mean" or "variability". Default is "mean".
`selectMean` | the mean of a metric. It is used when mean is known. It is NULL when mean is not known. The default is NULL.
`selectSD` | the standard deviation of a metric. It is used when standard deviation is known. It is NULL when mean is not known. The default is NULL.

### Value

A plot of likelihood statistics versus time per peptide and metric generated from `CP.data.prepare` data frame.

### Examples

    # First process the data to make sure it's ready to use
    sampleData <- DataProcess(S9Site54)
    head(sampleData)
    # Find the name of the peptides
    levels(sampleData$Precursor)
    # Calculate change point statistics
    ChangePointEstimator(data = sampleData, peptide = "VLVLDTDYK", metric = "BestRetentionTime")
    ChangePointEstimator(data = sampleData, peptide = "VLVLDTDYK", metric = "BestRetentionTime",
                         ytitle = "Change Point Plot - variability", type = "variability")
    ChangePointEstimator(data = sampleData, peptide = "VLVLDTDYK", metric = "BestRetentionTime",
                         selectMean = 27.78, selectSD = 8.19)
    ChangePointEstimator(data = sampleData, peptide = "DDGSWEVIEGYR", metric = "TotalArea")
    ChangePointEstimator(data = sampleData, peptide = "DDGSWEVIEGYR", metric = "TotalArea",
                         selectMean = 35097129, selectSD = 34132861)
    ChangePointEstimator(data = sampleData, peptide = "TAAYVNAIEK", metric = "MaxFWHM")
    ChangePointEstimator(data = sampleData, peptide = "LVNELTEFAK", metric = "Peak Assymetry")

[Package MSstatsQC version 2.4.0 Index]