iSixSigma

Wait Time Measurement

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  • #53387

    Trish G
    Participant

    I work for bank and am involved in a wait time improvement project in the branches. We are first attempting to develop a means of measuring current wait time in the teller line. The current process is rather sketchy…it is a “random” sample taken typically by branch staff at times designated that are picked randomly. We really don’t feel its effective, staff forgets to do the timings at the designated times…and /or they estimate etc.

    Management is interested in a sampling scheme as opposed to investing in a system that captures all the data continuously that would be a substantial initial investment. However, developing a sampling scheme for 20 branches in different areas with different demographics, peak times vs. slow times, relatively high branch staff turnover, different external events driving different peak times such as taxes, beginning and middle of month SS checks etc.

    Any thoughts around a sampling scheme, or how to best back up my hypothesis that a sampling scheme would not be very effective in this scenario?

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    #189914

    Hody
    Member

    In transactional services, it is quite useful to utilize “Little’s Law” to determine “Dynamic Lead Time” instead of sampling customers for their lead times.

    Focus on the average time spent per customer (which may vary at tax time or Fridays with more transactions per customer). All else you would need is to note the length of the customer line.

    If you determine that it takes an average of 4 minutes for a teller to service a single customer and if you have 2 tellers working, then you will average customers to be completed every 2 minutes. If there are 10 customers in line, then Little’s Law shows that last customer will have to wait 20 minutes until they get to the window.

    Does that help?

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    #189915

    Trish G
    Participant

    Sensei…it does, I had thought about Little’s Law early on…one of my concerns is the variation fo transaction time for customers .but I could look at the data around that to see how much variation there really is…thanks much

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    #190404

    Gilbert
    Member

    HI there, I am doing something similar only using the time spent to view a casting in our inspection booths. Can anyone explain a method of using the times gathered (I have circa 12000 records!) to carry out some analysis on?

    My main problem is that the distribution is non normal so I am a bit stuck for ideas to show variation in the lead time through the section….

    Please excuse my ignorance, I am a trainee black belt and have only been doing this kind of thing for about 3 weeks!

    I have tried transforming the data to normalise it but this puts the spread across zero which obviously does not refelct what is happening….

    Any advice on using the toolbox on time based, non normal data would be greatly appreciated!

    Many thanks in anticipation,

    Stu

    p.s. Sorry if I just hijacked your thread, I felt it was along the same lines! :)

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