You can do what you want easily if you declare your variable as discussed HERE.
So if we are to apply it, you can open your workbook like this:
Dim wb As Workbook
Dim myfilename As String
myfilename = "C:\Users\Ayaz\Desktop\Analysis\AvgStdev.xlsm"
'~~> open the workbook and pass it to workbook object variable
Set wb = Workbooks.Open(myfilename)
'~~> More codes here
Now later in your code if you are saving the same file:
wb.Save '~~> save
wb.Close '~~> close
Or you can do it using Close method only:
wb.Close True '~~> explicit SaveChanges argument to true
Now if however you like to save it as another file:
Dim newfilename As String
newfilename = "C:\Users\Ayaz\Desktop\Analysis\Another.xlsm"
'~~> If you are saving it in a format other than .xlsx,
'~~> you have to be explicit in the FileFormat argument
wb.SaveAs newfilename, xlOpenXMLWorkbookMacroEnabled
wb.Close
HTH.