R help - May 2013 - Calculates the mean/median from grouped data in R?

Is there a function in R that calculate the mean and median for a grouped
data?
For example, a survey shows the oil price outlook in the future. How can I
calculate the mean/median?
(Of course, I understand that the groups "below 80" and "above
110" must be
defined more specifically)

  below 80 4  80-90 5  90-100 8  100-110 7  above 110 3

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On May 7, 2013, at 8:40 PM, jpm miao wrote:
> Is there a function in R that calculate the mean and median for a grouped
> data?
> For example, a survey shows the oil price outlook in the future. How can I
> calculate the mean/median?
> (Of course, I understand that the groups "below 80" and
"above 110" must be
> defined more specifically)
> 
>  below 80 4  80-90 5  90-100 8  100-110 7  above 110 3
> 
Why would all groups need to be defined more specifically? How do we know
whether items in the 80-90 range are evenly distributed? .... could be 80, 81,
82, 84, 85 or all 89's.

David Winsemius
Alameda, CA, USA

see if this helps:

library(actuar)
data(gdental)    # grouped data
quantile(gdental)
mean(gdental)

Nuri

On Wed, 8 May 2013, jpm miao wrote:
> Is there a function in R that calculate the mean and median for a grouped
> data?
> For example, a survey shows the oil price outlook in the future. How can I
> calculate the mean/median?
> (Of course, I understand that the groups "below 80" and
"above 110" must be
> defined more specifically)
>
>  below 80 4  80-90 5  90-100 8  100-110 7  above 110 3
>
> 	[[alternative HTML version deleted]]
>
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