Laboratory turn around time (TAT)
Several clinicians in the A&E department have been
complaining that the turn around time (TAT) for complete
blood counts has been ‘‘out of control and constantly getting
worse’’. The laboratory manager decides to investigate this
assertion with data rather than just opinions. The data are
stratified by shift and type of request (urgent versus routine)
to ensure that the analysis is conducted by reasonably
homogeneous processes. Since TAT data often follow normal
distributions, X-bar and S types of control charts are
appropriate here (fig 2). Each day the mean and SD TAT
were calculated for three randomly selected orders for
complete blood counts. The top chart (X-bar) shows the
mean TAT for the three orders each day, while the bottom
chart (S) shows the SD for the same three orders; during the
day shift the mean time to get results for a routine complete
blood count is about 45 minutes with a mean SD of about
21 minutes.
If the clinicians’complaints were true, out of control points
and an overall increasing trend would be observed. Instead, it
appears that the process is performing consistently and in a
state of statistical control. Although this conclusion may not
agree with the clinicians’views, common cause variation does
not necessarily mean the results are acceptable, but only that
the process is stable and predictable. An in control process
can therefore be predictably bad.
In this case the process is stable and predictable but not
acceptable to the clinicians. Since the process exhibits only
common cause variation, it is appropriate to consider
improvement strategies to lower the mean TAT and reduce
the variation (lower the centre line and bring the control
limits closer together). This would produce a new and more
acceptable level of performance. The next steps for the team
are therefore to test an improvement idea, compare the new
process with these baseline measurements, and decide
whether the process has improved, stayed the same, or
worsened.
Laboratory turn around time (TAT)Several clinicians in the A&E department have beencomplaining that the turn around time (TAT) for completeblood counts has been ‘‘out of control and constantly gettingworse’’. The laboratory manager decides to investigate thisassertion with data rather than just opinions. The data arestratified by shift and type of request (urgent versus routine)to ensure that the analysis is conducted by reasonablyhomogeneous processes. Since TAT data often follow normaldistributions, X-bar and S types of control charts areappropriate here (fig 2). Each day the mean and SD TATwere calculated for three randomly selected orders forcomplete blood counts. The top chart (X-bar) shows themean TAT for the three orders each day, while the bottomchart (S) shows the SD for the same three orders; during theday shift the mean time to get results for a routine completeblood count is about 45 minutes with a mean SD of about21 minutes.If the clinicians’complaints were true, out of control pointsand an overall increasing trend would be observed. Instead, itappears that the process is performing consistently and in astate of statistical control. Although this conclusion may notagree with the clinicians’views, common cause variation doesnot necessarily mean the results are acceptable, but only thatthe process is stable and predictable. An in control processcan therefore be predictably bad.In this case the process is stable and predictable but notacceptable to the clinicians. Since the process exhibits onlycommon cause variation, it is appropriate to considerimprovement strategies to lower the mean TAT and reducethe variation (lower the centre line and bring the controllimits closer together). This would produce a new and moreacceptable level of performance. The next steps for the teamare therefore to test an improvement idea, compare the newprocess with these baseline measurements, and decidewhether the process has improved, stayed the same, orworsened.
การแปล กรุณารอสักครู่..
