below instruction is also answer to question:
How to update JoomlaStats from v2.2.4 to v3.0.0?
In few simple words:
1) Uninstall JoomlaStats component in Joomla 1.0.15 using standard Joomla CMS uninstall method
(joomla backend -> menu -> Installers -> Components -> uninstall JoomlaStats component)
2) Migrate Joomla CMS 1.0.15 to Joomla CMS 1.5.12
3) Simply install main component (com_joomlastats_v2.3.1.zip) in Joomla CMS 1.5.12, and all Your statistics will be retained
4) Uninstall JoomlaStats component com_joomlastats_v2.3.1.zip in Joomla 1.5.12 using standard Joomla CMS uninstall method
(joomla backend -> menu -> Install/Uninstall -> Components -> uninstall JoomlaStats component)
5) Uninstall "bot_jstats_activate" it is obsolete and could cause "Restricted Access"
6) Install main component (com_joomlastats_v3.0.0.zip) in Joomla CMS 1.5.12, and all Your statistics will be retained
6) Now You can turn of Legacy mode in Joomla CMS v1.5.12
Do not omit installing com_joomlastats_v2.3.1.zip
.
More detailed:
To migrate JoomlaStats to other Joomla CMS (like Joomla 1.5.12) You need only move JoomlaStats tables to the same database which Joomla is installed. Next step is simply to install new version of JoomlaStats component (like com_joomlastats_v2.3.0.zip).
Between main component versions 2.2.0 up to 2.5.0 You do not need any migration tool. Simply uninstall old version and instal new one.
JoomlaStats *.php files does not contain any significant data. They can be simply deleted but we do not recommend it.
JoomlaStats version v2.2.3 (com_joomlastats_v2.2.3.zip) can be installed (and uninstalled) on Joomla 1.5.12 (in Legacy mode) and works OK. It have missing graphics, but no problems with performance were detected.