How my school gamed the stats

I was reading the Slate Star Codex review of Rule of the Smart. Part of it discusses charter vs state schools and the allegations of fraud of various kinds undermining charter schools record of better achievement. Reading it, I realized that I took for granted that public schools engage in systematic fraud in a variety of ways. I don't think this is something everyone understands, hence this post. I went to a state school in the UK. State schools are rated on a 1 - 4 scale from unsatisfactory to outstanding. My school was rated good, meaning a 3. A few memories which stand out. During my first week I saw one of the boys in my class who was 11 at the time held up against the wall in a corridor while a 16 year old put a shiv to his throat and robbed him. He handed over his wallet and keys. A year or two later and I remember seeing a small boy who struggled with depression held up by the throat against a locker and slapped in the face by a troublemaker from the same class in front of everyone just before we went in to the classroom. I remember classes which were filled start to finish with people shouting and talking. Neither of the first two events were common but they also weren't uncommon. No one was surprised to witness them. It's worth emphasizing again that my school was above average, in fact quite far above average, and in a middle class area. It's also worth noting that I was mostly in top ability streamed classes, meaning my classroom experience was likely far better than average.