MSQC::mult.chart ignores xlim argument

Question

I computed Hotelling T2 on a normalized dataset and obtained the following chart in R:

In the chart, I want to study the interval 50-100 in the X-axis closely. Is there any function or method in R through which this can be done? Thanks.

Answer 1

Unfortunately, MSQC::mult.chart does not support xlim argument. But you can extract the values to plot and reproduce manually. See example below.

library(MSQC)
data(dowel1)
# default
mult.chart(dowel1, type = "chi", alpha = 0.05)
#> [[1]]
#> [1] "Chi-squared Control Chart"
#> 
#> $ucl
#> [1] 5.99
#> 
#> $t2
#>       [,1]
#>  [1,] 1.62
#> ...
#> 
#> $Xmv
#> [1] 0.5 1.0
#> 
#> $covariance
#>         [,1]    [,2]
#> [1,] 4.9e-05 8.6e-05
#> [2,] 8.6e-05 4.2e-04

# manual
mc <- mult.chart(dowel1, type = "chi", alpha = 0.05)
plot(seq_along(mc$t2), mc$t2, ylim = c(0, mc$ucl), type = "l")
points(seq_along(mc$t2), mc$t2)
abline(h = mc$ucl, col = 2)

# restricted
plot(seq_along(mc$t2), mc$t2, ylim = c(0, mc$ucl), type = "l", xlim = c(5, 20))
points(seq_along(mc$t2), mc$t2)
abline(h = mc$ucl, col = 2)

^{Created on 2019-02-10 by the reprex package (v0.2.1)}