what research methods are used to research in the below articles:

1. Media Managing Mood: A Look at the Possible Effects of Violent Media on Affect

https://content.ebscohost.com/ContentServer.asp?T=P&P=AN&K=113393217&S=R&D=asn&EbscoContent=dGJyMNLr40SeqLY4xNvgOLCmsEuep7VSsKa4SLCWxWXS&ContentCustomer=dGJyMPGptkmzrbVNuePfgeyx43zx

2. Violent Movies and Severe Acts of Violence: Sensationalism Versus Science

https://content.ebscohost.com/ContentServer.asp?T=P&P=AN&K=101603338&S=R&D=ufh&EbscoContent=dGJyMNLr40SeqLY4xNvgOLCmsEuep7VSsay4TK6WxWXS&ContentCustomer=dGJyMPGptkmzrbVNuePfgeyx44Dt6fIA

3. Effect of movie violence on mood, stress, appetite perception and food preferences in a random population

https://content.ebscohost.com/ContentServer.asp?T=P&P=AN&K=108721718&S=R&D=asn&EbscoContent=dGJyMNLr40SeqLY4xNvgOLCmsEuep7VSsqm4SLeWxWXS&ContentCustomer=dGJyMPGptkmzrbVNuePfgeyx44Dt6fIA