问题 单项选择题

统计的重要工作就是对资料进行统计描述。对偏态分布的统计资料进行集中趋势统计描述的常用指标是( )。

A.算术平均数
B.几何平均数
C.中位数
D.加权平均数

答案

参考答案:C

解析:(1)算术平均数
简称均数,有总体均数和样本均数之分。
(2)几何平均数
适用于呈倍数关系的等比资料或对数正态分布的资料,应用中应注意观察值不能同时有正有负,同一资料算得的几何均数小于算术均数。
(3)中位数(Median)
中位数是一组观察值的位置平均数,直接由原始数据计算中位数时,若n为奇数,则中位数为将观察值从小到大排序后中间位置那个观察值,若n为偶数,中位数为将观察值从小到大排序后中间两个观察值的算术均数。在实践中常用于偏态分布资料和分布两端无确定值的资料。中位数用于描述偏态分布资料的集中位置,它不受两端特大、特小值的影响,当分布末端无确切数据时也可计算。
百分位数是资料分布数列的百等份分割值,百分位数用于描述样本或总体观察值序列某百分位置的水平,应用中注意,样本例数不够多时,两端的百分位数不稳定。百分位数还用于确定参考值范围。

选择题
阅读理解

We all make excuses.

But the successful ones are those who can kill the excuses like the miserable maggots they are.

I’m too tired. I don’t have the time. I don’t feel motivated. I’d rather do nothing. I don’t have the money, equipment, space. I can’t because …

We’ve all made the excuses. Here’s how to kill them.

See the positive. Excuses are usually made because we don’t feel like doing something — we’re accentuating the negative. Instead, see the fun in something, the joy in it. And maintain a positive attitude, or you’ll never beat the excuses.

Take responsibility. Excuses are ways to get out of owning up to something. If we don’t have the time, money, equipment, etc., then it’s not our fault, right? Wrong. Take responsibility, and own the solution.

Find a solution. Just about every problem has a solution. Don’t have time? Start with just 5-10 minutes. Make the time. Wake earlier. Do it during lunch. Don’t have the energy? Do it when you have higher levels of energy. You’re smart. Figure out the solution.

See your goal. This is your motivation — your reason for doing it. Sure, you could just lay on the couch, but if you think about why you really want to pursue a goal, you’ll be motivated. Visualize that goal and just get started.

Be accountable. Have a workout partner, a project partner, a team, someone to report to. If you have to meet a coach or partner, you’re more likely to do something.

Watch this. Then go an do it.  

小题1:How many tips mentioned in the text to prevent excuses?

A.Four

B.Three

C.Six

D.Five小题2:The second paragraph is developed mainly by _______

A.providing common examples.

B.following the order of time.

C.making comparisons of excuses.

D.analyzing common excuses小题3:The definition of the underlined word” visualize” would most probably be ______

A.to view the outline of something by means of an X-ray.

B.to weaken or spoil the quality or efficiency of something.

C.to form a mental image of something incapable of being viewed.

D.to express the formal image of something capable of being seen.小题4:Why do you need a partner according to the passage?

A.because you are likely to make a report to someone.

B.because it’ll be more possible for you to do something wih a partner.

C.because you need a coach to help you do something.

D.because you like to do something with a partner or a coach.