Excel Graph Help

In the above graph there is a line on graph which indicates mean value. Will any one explain me with an example(how to write values, mean value and which chart format I have to choose etc) on how to make a graph like this. I am using excel 2007.

Thanks in advance

 

Do you mean a mean luminance between the three groups (HID1, HID2 and HLB)?

 

Desr slurpee55,

Above chart is just for reference to show the single line on the graph bar. (on dog bar a line is ending at approximately at 2.4 and started at 0.6) Like this I want draw a chart.

 

Bars like those are usually range markers - the highest and lowest points in the data being marked by the, in this case, 2.4 and .6. If you want to show those, click on a column in your graph, go to Format Data Series, Go to the Y Error Bars tab and click Both. If you make it a percentage and set that value to 50, it will show you a bar going down and stopping at the 50% and going up and stopping 50% above the data column.
I just find it easier, however, to calculate the mean next to the original data and include that column of data in the graph also.