The `metamean` function in R is typically used for meta-analysis, where you combine summary statistics from multiple studies to calculate an overall estimate. In your case, you can use both types of data to calculate an overall mean PCB concentration.

For individual mammals, you can simply use the reported values as they are. For studies reporting mean concentrations for a sample size, you'll need to calculate a weighted mean.

Here's a general approach:

1. For studies reporting individual PCB concentrations, use those values directly.

2. For studies reporting mean concentrations for a sample size:

a. Calculate the weighted mean by multiplying the mean concentration by the sample size.

b. Sum up these weighted mean values across all studies.

c. Divide the sum by the total sample size to get the overall mean concentration.

Make sure to appropriately weigh the studies based on factors like sample size and study quality to ensure a robust overall estimate.

Reuben Osei

Thankyou very much. Is there any webpage that has easy to follow code for metamean. also I'm not sure if I can actually do a statistical test on the results as PCB'S are made up of different parts which not all studies look at the same ones