When I upgrade or install WP Statistics I get an error message like

Parse error: syntax error, unexpected T_STRING, expecting T_CONSTANT_ENCAPSED_STRING or '(

Since WP Statistics 8.0, PHP 5.3 or above has been required. If you are using an older version of PHP it cannot understand the new syntax included in WP Statistics 8.0 and generates a parse error.

Your hosting provider should have a newer version of PHP available, sometimes you must activate it through your hosting control panel.

Since the last release of PHP 5.2 is over 5 years ago (Jan 2011) and is no longer supported or receiving security fixes, if your provider does not support a newer version you should probably be moving hosting providers.

If you have done an upgrade and you can no longer access your site due to the parse error you will have to manually delete the wp-statistics directory from your wordpress/wp-content/plugins directory, either through your hosting providers control panel or FTP.

Do not use older versions of WP Statistics as they have know security issues and will leave your site vulnerable to attack.