can any body tell me that why my alexa rank is falling down ,however the visitor on the site is going up day by day
I had one site that barely had any traffic, but was ranking higher than a lot of other sites that did. So I would have to say no, it is not accurate measurement of traffic.
Hell no. You can have two sites, one getting ten times the traffic of the other, yet still the two sites are similarly ranked.
Gazan4u has it in one. They take the stats from people using the alexa toolbar and extrapolate that out to the entire internet. All it takes is a handful of alexa toolbar using mates and you can artificially inflate your site's alexa rank no end.
Alexa rank is only an indicator of visitors - i.e. when visitors increases your rank goes down and when the visitors goes down your ranking increases. It does not indicate exact number of visitors at any moment.
People shouldn't really be assuming that every KPI out there is accurate. No KPI out there is perfect or 'good' enough to give accurate results. Just take them as an indicator (hence the name KPI) and more of a guide rather than a factual data.
there are still many things in Alexa ranking which need improvement. so, i can't say alexa ranking is accurate.
Alexa is not accurate as far as the total number of visitors due to reasons previously stated. It is also not accurate if you are checking how your site ranks or stacks up against another site because Alexa will not have enough statistically significant data for sites with low traffic. I think it is a good traffic ranking indicator for large sites when enough data is collected.
Alexa rank increases only if your site's visitors have alexa tool bar installed in their browser. Alexa rank need not to be considered as an important factor. It calculates the rank with data from the tool bar and add some other data in calculating the alexa ranking.
Alexa is a pretty powerful tool that you can use. There's a lot of controversy about how effective Alexa really is. To be quite honest, Alexa is a lot more effective than most of what is out there. We follow our Alexa rankings on our systems on a daily basis with a 4 figure daily and monthly average for both Worldwide and US based traffic. Having a low Alexa rank shows that your website receives a substantial amount of traffic and gives very good statistics about how your website is ranked, as well as, how your website is performing and perceived by everyone on the internet.