arbitron: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/lib/cyrus/bin/arbitron - from package: cyrus-common

You may install the required package with command apt-get install {package}
Error in other languages:
arbitron: bevel nie gevind nie
arbitron: comandă negăsită
arbitron: comando não encontrado
arbitron: commande introuvable
arbitron: command not found
arbitron: käsku ei ole
arbitron: không tìm thấy lệnh
arbitron: komanda nerasta
arbitron: Kommando nicht gefunden.
arbitron: kommandot finns inte
arbitron: komut yok
arbitron: nie znaleziono polecenia
arbitron: níor aimsíodh an t-ordú
arbitron: no se encontró la orden
arbitron: no s'ha trobat l'ordre
arbitron: opdracht niet gevonden
arbitron: parancs nem található
arbitron: perintah tidak ditemukan
arbitron: príkaz nenájdený
arbitron: příkaz nenalezen
arbitron: команда не найдена
arbitron: командата не е открита
arbitron: 命令找不到
arbitron: コマンドが見つかりません