passing a range object to a sub in VBA - vba

Question

Trying to create a subroutine that takes a range cell and calculates the average of the cells in that column. But I get the error: Object Required
How can I correct this?
Sub test()
Dim rg As Range
Set rg = ThisWorkbook.Worksheets(1).Range("B1")
ColumnAverageToTop (rg)
End Sub
Sub ColumnAverageToTop(rg As Range)
'calculates the average of the data in column and puts it above the data
Cells(1, rg.Column).End(xlDown).Offset(1, 0).Value = Application.WorksheetFunction.Average(rg.Columns(rg.Column))
End Sub

Answer 1

Good that there's a comment that is telling what this sub should do: I read it as: If I run "Test()", the following happens: in the passed range's column in row one, the average of that column's values should appear.
There are three problems in your code.
The first is mentioned in previous comments: Use either call ColumnAverageToTop(rg) or ColumnAverageToTop rg in your test-routine. Solution:
Sub test()
Dim rg As Range
Set rg = ThisWorkbook.Worksheets(1).Range("B1")
ColumnAverageToTop rg
End Sub
Now that we will succesfully enter the ColumnAverageToTop routine, there's an issue with passing the parameter to the WorkSheetFunction.Average
It takes arguments as documented here: https://msdn.microsoft.com/en-us/library/office/ff836809.aspx so to keep it simple just make sure to pass a Range-object to it on which the calculation is performed.
Lastly, when using End and Offset, make sure you use them in the right order. Each of these functions will provide a new range object. I see you attempt to get the cell below the passed argument and then go down and get all the other values to calculate the average of that range.
If you truely always need the average of the entire column, I would advise:
Sub ColumnAverageToTop(rg As Range)
'calculates the average of the data in column and puts it in row 1 of column
'We declare where we put the value: Cells(1,1) of the column of the Range passed
'E.g. "B1" passed means that the average will be in "B1".
'Same fore passing "B323"
rg.EntireColumn.Cells(1, 1).Value = WorksheetFunction.Average(rg.EntireColumn)
End Sub
This will include any numerical value in row 1 of the same column of the passed range, even though it will be overwritten with the result. Running the same test multiple times will therefore change the result.
If you really need the average of everything below the 1st row until the first blank row, it should be:
.rg.EntireColumn.Cells(1,1).value = WorksheetFunction.Average(rg.EntireColumn.Range(Cells(2, 1), Cells(2,1).End(xlDown)))
If your need the average of the filled cells below the referenced cell:
.rg.EntireColumn.Cells(1, 1).Value = WorksheetFunction.Average(rg.Offset(1, 0).Resize(rg.Offset(1, 0).End(xlDown).Row - rg.Offset(1, 0), 1))
Hope this helps you out.