To increase website visits should not be the main reason why a museum joins social networks but it is nevertheless a plausible goal to include in the museum social media strategy.
"As you probably noticed 17% of visits via social referral is quite high. A more usual result would vary between 1% and 3%, which might probably means that your organisation’s website has a multitude of important referrals and it does not exclusively depend on social networks. What are the social networks that drive more traffic to your website? Is it Facebook, Twitter or any other? What is the percentage of social referral for your organisation’s website? Sharing this information with others affords us the possibility to better understand our individual strategy and it will definitively put some of this abstract numbers back in context."
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