(1) 考虑以下一组数字：12, -25, 2, 3, 21, 8, 10, 14, 3, 18, 21。对于下面的每个问题，陈述你的答案，并在必要时显示有效。

（一种）。什么是极差和四分位距？

(b)。假设总和 (Px) 为 87，平方和 (Px2) 为 2357，那么样本标准是多少

（C）。识别候选异常值并使用异常值计算新的样本标准偏差

(2) 假设两个定量变量 x 和 y 具有负相关。关于他们的关系，我们能说些什么？

2. 概率

(1) 你正在研究一种新的减肥药的副作用。您招募了 500 名肥胖患者及其

• 试验开始时的重量
• 12 个月时的体重
• 12 个月时的并发症

(1) Consider the following set of numbers: 12, -25, 2, 3, 21, 8, 10, 14, 3, 18, 21. For each of the questions below, state your answer, showing working if necessary.

(a). What is the range and the inter-quartile range?

(b). Given the sum (Px) is 87 and the sum of squares (Px2) is 2357, what is the sample standard
deviation?

(c). Identify a candidate outlier and compute a new sample standard deviation with the outlier
removed.

(2) Suppose two quantitive variables, x and y, have a negative correlation. What can we say about their relationship?

2. Probability

(1) You are studying the side-eﬀects of a new weight loss drug. You enroll 500 obese patients and their
GPs to do a long term trial of the drug. You have GPs ﬁll out a table for their patients with entries
as follows:

• weight at start of trial
• weight at 12 months
• complications at 12 months

You then plan to do an analysis of the complications and weight loss. But 178 patients drop out of the study before the end of the 12 months. What potential problems are their with your design? Is there any sampling bias in the recording of complications, and if so what is it called?