Hello, I'm working on setting new performance goals for my business
group. The metric I'm working on is average talk time for a customer
service call. The goal would be to end the month equal or lower than
the goal. Below is the data for the past 13 months:
5.48 5.61 5.70 6.09 6.13 5.80 5.64 5.63 5.72 5.81 5.91 5.98 5.99


I need to create a formula that will calculate a new target goal that
will have an 80% probability of being successful based on the
historical data for the past 13 months.

Any help would be greatly appreciated. If you have any questions or
need more data, please respond to this post and I can review ASAP.

dlharting -

I suggest that you first "look at the data." Create a Line chart.

Decide whether there's any seasonality (high in months 4 and 5, low in 7 and
8). Use your judgment. If there's systematic variation, take it into account
in predicting the future.

Instead, if you regard the past as equally-likely values for the future
(i.e., you have no other information that's relevant), then rank the 13
values from lowest to highest, and pick the value with rank 0.8*13 = 10.4,
i.e., the value with approximate rank 10, which is 5.98.

- Mike Middleton
http://www.MikeMiddleton.com
Software and Books for Decision Analysis and Data Analysis



wrote in message
...
Hello, I'm working on setting new performance goals for my business
group. The metric I'm working on is average talk time for a customer
service call. The goal would be to end the month equal or lower than
the goal. Below is the data for the past 13 months:
5.48 5.61 5.70 6.09 6.13 5.80 5.64 5.63 5.72 5.81 5.91 5.98 5.99


I need to create a formula that will calculate a new target goal that
will have an 80% probability of being successful based on the
historical data for the past 13 months.

Any help would be greatly appreciated. If you have any questions or
need more data, please respond to this post and I can review ASAP.