Inferential Statistics

CHAPTER ELEVEN

Inferential Statistics

Zacharias Smith accosted me at break the next morning with a cheery, "Mike, my boy, I'm thinking you're the only person who'll understand me!"

"What's up?"

"Can you send your friend away?"

Terry shrugged and walked across the courtyard. Out of the corner of my eye, I saw him approaching Sally-Anne Perks and Sophie Roper.

"Michael, I'm wanting your opinion. When are you reckoning it's okay to change your mind about an appointment?"

I hadn't a clue what he meant. "Er ... whenever you can warn the other person in time, I suppose. Assuming you're cancelling because something more important turned up."

"Yes, but what counts as more important? You see, I've changed my mind about the Yule Ball." He paused importantly.

"You mean you don't want to go any more and you don't know how to tell Parvati Patil?"

"No, I'm meaning I'd rather go with a different girl, and I'm not knowing whether to tell Parvati Patil."

"Well, that would make you a bit of a Zabini, wouldn't it?" I was irritated that Zacharias couldn't see this. "I mean, assuming the girl hasn't behaved badly. If you liked her enough to invite her, you ought to like her enough to take her, even if you've found out she's really a second-best."

Zacharias drooped for an instant, then squared his shoulders defiantly. "I'm not like Zabini, Mike. When I first asked Parvati Patil, I was meaning to take her. Zabini's never meaning it, is he? So I'm not like him. But I've changed my mind about Parvati since asking her. Do you get the difference?"

"Yes, I get the difference, but – "

"You see, I basically asked Parvati because she's good-looking. And it's pretty obvious that she accepted me because she was going to accept anybody who asked. Which are not the best reasons to go together."

"No, they're not, but they're okay reasons if both of you agree – "

"And now I've got to know a girl whom I really, really like. So I'm asking you, as a person who despises Zabini, if you think – "

"Zacharias, I thought I'd explained what I think," I cried in exasperation. "You put yourself in this situation. You should stick with it. Not that Parvati has to be your girlfriend, just that you should still go to the ball together. If the other girl's so wonderful, surely she'll understand that the two of you can get together after the ball?"

"And I suppose you're thinking your opinion is all-important in this matter that's not your business?" spat Zacharias angrily.

"Well, I suppose there is one honourable way out," I ventured. "Something Zabini would never do, but anyone I really respected would try."

He softened very slightly.

"You could tell Parvati the truth. Say that she's the one you'll be taking to the ball – as a friend – but that you've met someone you like better. And if Parvati has any sense of honour, it might turn out that she suggests that you take the other girl instead of herself."

Zacharias relaxed and half-smiled at me. "Brilliant advice! That's what I'll do. Thanks, mate!"

And he walked away, apparently not hearing as I called after him, "But say it tactfully!"

Great, I thought. Now we'll have Padma and Parvati desperate and dateless and dolorous. A rather surprising fate for the two most attractive girls in fourth year.

Dinner that evening was quite lively. It was the last term-time dinner, and spirits were extremely high. I arrived just as Filch was sending one of the Gryffindor Beaters out of the hall for letting off a firework at the dinner table. Plenty of people were wandering about at the wrong tables. Zacharias was at the Slytherin end, whispering to Tracey Davies, who was all smiles this evening. Zabini was with the Hufflepuffs, where Megan Jones was staring into his eyes and laughing at something he had said. At the Ravenclaw end nearest the door, Lisa was staring furiously at Zabini.

"Don't tell us," I said as I slid onto the bench next to Lisa. "Zabini invited you to the Yule Ball."

She was only mildly surprised that I knew. "I refused him, of course," she said. "But I can't believe Megan Jones. It looks as if she's accepted!"

"You know about this bet, then?"

"Bet? No!"

I explained, including the Silencing Varnish, and Lisa only said: "Well, I should have known it were something like that, love. I know for a fact that he asked Susan Bones this morning. She tried to tell me during History of Magic, but she didn't seem to be able to get t' words out. Then, after lunch – that is, after Zabini had asked me too – Susan tried again, and this time she had no trouble, she could tell me easy. Oh, don't worry, Susan refused him! But it looks as if some of t' others are daft enough to flatter his vanity."

I wondered who would be willing to flatter my vanity. Either Susan or Lisa would be as good a choice as anyone. "So," I said, "you're already going with someone, right?"

"Well, I weren't when Zabini asked me. But Kevin overheard what I were saying to Susan, and he invited me to be his partner on the spot."

"Did you accept him?"

"Yes, I like Kevin."

"What about Susan? Who's taking her?"

"No-one yet, but Justin Finch-Fletchley asked Kevin to ask me if he had a chance – if Justin had a chance with Susan, I mean – and I said yes, a very good chance."

"That's the trouble," I said to Terry in the common room. "All the nice girls seem to be taken."

"Oh, not all of them," said Terry breezily. "People exaggerate how embarrassing it is to ask a girl out, you know. You just have to choose your words in a way that leaves her free to answer either way."

"Oh, so Sally-Anne Perks accepted you, did she? What did you say to her?"

"I asked if she had a partner for the ball, and she said no. So I asked if she'd like to go with me and she said yes. And – well, anyway, you get the idea."

"You cheated," I said. "You already knew she liked you."

"That isn't cheating, that's just common sense. Lots of boys research a girl before asking her."

"But I don't have anyone to research!" I complained.

"Rubbish, there are equal numbers of boys and girls and Hogwarts, aren't there?"

"Actually, there aren't." Anthony Goldstein looked up from his book. "Not any more. You've forgotten about the Durmstrang students. They brought nine boys and only three girls. So there are six extra boys running around the school and not enough girls to go with them."

I blinked. How simple! Why hadn't anyone thought of this? "Plus there's Penelope Clearwater," I remembered. "Her boyfriend from the Ministry will be coming to the ball. So actually there are seven girls too few."

"It's just statistics," agreed Anthony. "Anyone who can add up ought to know that. Obviously, the Durmstrang students will invite the seventh- and sixth-year girls. So the spare boys will invite the fifth- and fourth-year girls. That's why so many of the girls are going with older boys."

"So they are." I hadn't thought of it that way before. "Eddie Carmichael's taking Sophie Roper."

"And I heard that Sylvia Fawcett's going with Stebbins in Hufflepuff," recalled Terry.

"And that Gryffindor couple – Hooper asked Emma Spinks," said Anthony. "There are probably other examples too. But hardly any of the boys are going with an older girl. Well, you get the point. There's only one thing for it – "

"Go alone, and don't be embarrassed! At least six other boys will be in the same position! Thanks, Anthony, I will go only for the food!" I might as well, I thought. There was no-one I particularly wanted to take, and I couldn't be bothered going through the agony of asking if I was likely to be refused.

A group of fifth-year girls came and sat in the long sofa next to the fire. "I'll demonstrate your statistics, Anthony," I said, quite cheerful about the whole situation now. I addressed the most shatteringly beautiful girl in the group. "Cho, would you like to go to the ball with me?"

"I'm really sorry, Michael," she said, "but I've already promised to go with someone else."

"Marietta," I shifted my gaze to her pretty friend, "will you go to the ball with me?"

Marietta Edgecombe looked startled, as if she didn't know whether I were joking or not. "Thanks, but I'm going with Harold Dingle," she said.

"Sylvia," I moved to the next in line, "will you – "

"Oh, this is a joke!" exclaimed Sylvia Fawcett. "These boys have some kind of plot to invite every girl who sits on this sofa."

Sylvia and Marietta exploded into deafening giggles while Cho jumped up and led the way over to a different seat. I watched them leave. Really, I thought, all girls were more or less pretty. And Cho Chang was probably the most beautiful girl I had ever seen in my life.

"So are you taking anyone to the ball, Anthony?" asked Terry.

"Yes, as a matter of fact, I struck lucky," said Anthony. "I'm going with Su. I was asking her about the ball while we were making that heartsease potion. She said that she had had a partner lined up – she wouldn't tell me who he was – but they'd changed their minds. So I asked her to go with me, and she said yes."

Well, it sounds as if I know who Anthony's rival was, I thought.

"But, you know, I wasn't going to suggest that boys without partners go to the ball alone," Anthony continued. "What I was going to say was, you can always ask a third-year. It's statistics. Because third-years can't go to the ball at all unless someone older takes them. So third-year girls are quite likely to be available. And they're quite likely to say yes. They'd only say no to a boy whom they really hated."

And Anthony turned his nose back to his book. It was a Muggle publication called Intermediate Inferential Statistics.

I turned over in my mind whether I'd like to invite a third-year girl to the ball. I wasn't sure I wanted to find out that someone really hated me. But there must be one ... somewhere ... who could accept an evening with me as the price of attending the ball.