An HIV educator wishes to determine whether the method of delivering teaching influences adherence with antiretroviral therapy. She decides to measure adherence as viral load (a ratio measure). She teaches one group using lecture-discussion techniques. She adapts the information for access on the internet and gives another group the information using this medium. For yet another group, she decides to give a CD Rom for home study and then meets with individuals to answer any questions. She obtains viral loads for all clients for comparison. What procedure will determine the significance of any differences?