`"xbar"`

and plot the histogram.`process.capability(object,spec.limits, target, std.dev, nsigmas, confidence.level = 0.95, breaks = "scott", add.stats = TRUE, print = TRUE, digits = getOption("digits"), restore.par = TRUE)`

object

a 'qcc' object of type

`"xbar"`

spec.limits

a two-values vector specifying the lower and upper specification limits. For one-sided specification limits, the value of the missing limit must be set to

`NA`

.target

a value specifying the target of the process. If missing the value from the 'qcc' object is used if not

`NULL`

, otherwise the target is set at the middle value bewteen specification limits.std.dev

a value specifying the within-group standard deviation. If not provided is taken from the 'qcc' object.

nsigmas

a numeric value specifying the number of sigmas to use. If not provided is taken from the 'qcc' object.

confidence.level

a numeric value between 0 and 1 specifying the level to use for computing confidence intervals.

breaks

a value or string used to draw the histogram. See the help for

`hist`

for more details. add.stats

a logical value indicating whether statistics and capability indices should be added at the bottom of the chart.

print

a logical value indicating whether statistics and capability indices should be printed.

digits

the number of significant digits to use.

restore.par

a logical value indicating whether the previous

`par`

settings must be restored. If you need to add points, lines, etc. to a chart set this to `FALSE`

.- nobs
- number of obserations
- center
- center
- std.dev
- standard deviation
- target
- target
- spec.limits
- a vector of values giving the lower specification limit (LSL) and the upper specification limit (USL)
- indices
- a matrix of capability indices ($C_p$, $C_pl$, $C_pu$, $C_pk$, $C_pm$) and the corresponding confindence limits.
- exp
- a vector of values giving the expected fraction, based on a normal approximation, of the observations less than LSL and greater than USL.
- obs
- a vector of values giving the fraction of observations less than LSL and greater than USL.

`qcc`

```
data(pistonrings)
attach(pistonrings)
diameter <- qcc.groups(diameter, sample)
q <- qcc(diameter[1:25,], type="xbar", nsigmas=3, plot=FALSE)
process.capability(q, spec.limits=c(73.95,74.05))
process.capability(q, spec.limits=c(73.95,74.05), target=74.02)
process.capability(q, spec.limits=c(73.99,74.01))
process.capability(q, spec.limits = c(73.99, 74.1))
```

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