I don't care about alexa rank just because many sites are based on traffic exchange to increase their ranks however if website is sharing google analytics visits it will be more reliable to me because they ignore traffic exchange. Imagine if a website hoster is buying 1000 hits from easyhits4u then he will have 1000 visits per day however in reality 140 person surfing and visiting website again and again. Some admins make 24 unique traffic however it remains the same strategy getting 140 visits per day will falsify rank.