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统计学中有很多概念很抽象不容易理解,但是如果有恰当的例子作桥梁,就可以深入浅出,容易让人领悟了。

最近尝试学习一些关于项目反映理论(IRT)的东西,觉得很多学习资料都使用公式吓唬人,并没有把这个概念浅显化和生活化。总之,这些资料不够友好,让初学者望而生畏。

那么什么是项目反映理论呢?我试着解释解释。这样从测量开始说起。举个例子,推铅球比赛。每个运动员都会按照规定选择一定大小的铅球站在指定的地点,用尽全力把球向着一个方向推出去。然后裁判会用尺子测量落地点与原点的距离,读出读数作为成绩。实际上测量的是选手的推力和推送技巧,它有一个理论的真值。而裁判的读数则是观测值。但是理论值并不等于观测值。理论值=观测值+误差。这就是经典的测量理论。但是铅球有不同重量和大小,假如在比赛记录中,有两个不同时期的运动员,一个用的是15斤,一个是10斤,前者推了15米,后者推出了20米,那么那个选手的成绩更好呢。这个时候经典测验理论就无能为力了,要解决这个问题必须要再把两个运动员找来,用同一个铅球重新比过。但是项目反映理论则可以解决这个问题。

实际上,教育测量往往比这个情境还要复杂。推铅球我们还能直接测量然后读数,即使有误差,多测几次就能减少误差。当是教育测量则通常是纸笔测验,这个题答对那个题每答对,最后有个总分。那么这个总分就是我们学生的学业能力吗?当然不是,比如这张试卷一共十个题目。有些简单题目很多人答对,有些难题则很少人答对。假如有两个学生都得了8分。一个学生把难题都做对了,但是简单题却错了两个。另外一个则是两个最难的题目都做错了。那么他们的学业能力真的一样吗?你觉得谁的学业能力应该更强一些?(想一想)

如何思考这个问题呢?我们还是用推铅球这个例子。由于某种原因,我们无法直接测量了,比如没有尺子并且是夜晚。那怎么比赛呢,于是我们选几个离河边远近不同的几个测试点,然后在每个点放一堆大小相同的铅球。虽然我们不能测量,但是我们仍然能区分铅球是否落水,听到落水声就得1分,否则0分。就好像做选择题,我们能判断是否选择了正确的选项。由于每个测试点离河边远近的距离都不同,铅球的大小也不同,而且河岸的形状也有变化,所以每个测试点的难度也不同。但是同一个选手在状态相同的情况下,测试结果理论上是相同的。我们将会根据每个测试点选手的表现来估计其能力水平。如果按照总分把所有选手分成高分组和低分组,对于同一个测试点,我们会发现高分组的通过率会高于低分组,如果从群体中随机选取一个选手的话,来自高分组的选手将会有更高的概率通过,而低分组的选手则通过率会比较低。如果我们以选手的能力为横坐标,以通过某个测试点的概率为纵轴,那么就得到下面的曲线。
IRT ICC 项目特征曲线

从这个项目特征曲线中我们可以看到,随着能力(theta)的提高,答对这个题目的概率也在提升。不同题目的曲线也不同,也许你已经想象出一道更简单题的题目的项目特征曲线将会相对这条曲线左移,而难题的曲线则右移。假如通过大量的测验知道了每个题目的项目特征曲线,那么我们就可以根据选手对一组题目的作答情况来估测其能力水平。即便是两个选手作答的两组试题并不相同,我们也能够比较两个选手的能力高低了。

当然项目特征曲线有简单的也有复杂的,简单1个参数(难度),也有2个(难度,区分度)或3个参数(难度,区分度和猜测参数)的,也就是所谓1P模型,2P,3P模型。

了解更多关于IRT的知识,请参考学习资料见:IRT learning resources - Chunlei’s Blog

为了更好解释项目反映理论,我曾经想过很多其他的例子,但是还是觉得推铅球这个例子最好,最能深入浅出,又不失去科学性。但是好的例子往往不是一下子就想到的,而且往往需要比较后才能选择出来,我以前想到的例子也列出来,读者可以自己比较比较。

A 抛硬币或者骰子
B 测量身高
C 摸高
D 跳高

比较的依据:
1 是否用来衡量某种能力
2 是否可测量,与经典测量理论相联系
3 群体的这种能力的分布是否为正态分布
4 是否能解决不同尺子测量结果比较的问题

There are a lot learing resources for IRT(Item Response Theory). But the most useful onese are those fit you well.

Here is a list which helped me a lot.
Books:
The Basics of Item Response Theory: Frank B. Baker: 9781886047037: Amazon.com: Books-link
Item Response Theory: Parameter Estimation Techniques, Second Edition (Statistics: A Series of Textbooks and Monographs): Frank B. Baker, Seock-Ho Kim: 9780824758257: Amazon.com: Books link

Vedios:
A Conceptual Introduction to Item Response - YouTube

Pdf Documents:
A visual guide to item response theory VisualIRT.pdf
IRT mini-tutorial interactive
The Basics of Item Response Theory (by Frank Baker)

Slides:
IRT - Item response Theory
基于项目反映理论_宋慧鹏

Websites:
Item Response Theory GOOD
Item Response Theory cas.usf.edu

Softwares:
SSI - Scientific Software International, Inc.
WinGen: Windows software that Generates IRT parameters and item responses

Seven Principles for Good Practice in Undergraduate Education (Chickering & Gamson, 1987):

  1. Good practice encourages interaction between students and faculty.
  2. Good practice encourages interaction and collaboration between students.
  3. Good practice uses active learning techniques.
  4. Good practice gives prompt feedback.
  5. Good practice emphasizes time on task.
  6. Good practice communicates high expectations.
  7. Good practice respects diversity—talents, experience, and ways of learning.

Seven Learner-Centered Principles to Improve Teaching (Ambrose et al., 2010):

  1. Students’ prior knowledge can help or hinder learning.
  2. How students organize knowledge influences how they learn and apply what they know.
  3. Students’ motivation determines, directs, and sustains what they do to learn.
  4. To develop mastery, students must acquire component skills, practice integrating them, and know when to apply what they have learned.
  5. Goal-directed practice coupled with targeted feedback enhances the quality of students’ learning.
  6. Students’ current level of development interacts with the social, emotional, and intellectual climate of the course to impact learning.
  7. To become self-directed learners, students must learn to monitor and adjust their approaches to learning.

Principles based on brain science(Zull, 2002):

  1. recognize the importance of emotion.
  2. help students feel in control of their learning.
  3. build on existing neuronal networks (prior knowledge), even if these networks are wrong.

The following was added 2015-02-28

Glaser’s Seven Principles of Instruction

1 Structured Knowledge.
‘Instruction should foster increasingly articulated conceptual structures that enable inference and reasoning in various domains of knowledge and skill’ (17).

2 Use of Prior Knowledge and Cognitive Ability.
‘Relevant prior knowledge and intuition of the learner is … an important source of cognitive ability that can support and scaffold new learning … the assessment and use of cognitive abilities that arise from specific knowledge can facilitate new learning in a particular domain’ (18).

3 Metacognition Generative Cognitive Skill.
‘The use of generative self- regulatory cognitive strategies that enable individuals to reflect on, construct meaning from, and control their own activities … is a significant dimension of evolving cognitive skill in learning from childhood onward… These cognitive skills are critical to develop in instructional situations because they enhance the acquisition of knowledge by overseeing its use and by facilitating the transfer o

4 Active and Procedural Use of Knowledge in Meaningful Contexts.
‘Learning activities must emphasize the acquisition of knowledge, but this information must be connected with the conditions of its use and procedures for its applicability… School learning activities must be contextualized and situated so that the goals of the enterprise are apparent to the participants’ (19, emphasis in original).

5 Social Participation and Social Cognition.
‘The social display and social modelling of cognitive competence through group participation is a pervasive mechanism for the internalization and acquisition of knowledge and skill in individuals. Learning environments that involve dialogue with teachers and between peers provide opportunities for learners to share, critique, think with, and add to a common knowledge base’ (19)

6 Holistic Situations for Learning.
‘Learners understand the goals and meanings of an activity as they attain specific competencies… Competence is best developed through learning that takes place in the course of supported cognitive apprenticeship abilities within larger task contexts’ (19-20).

7 Making Thinking Overt.
‘Design situations in which the thinking of the learner is made apparent and overt to the teacher and to students. In this way, student thinking can be examined, questioned, and shaped as an active object of constructive learning’ (20).

Psychologists Identify the Best Ways to Study

click here for more details

  1. Self-Testing: Quizzing Yourself Gets High Marks
  2. Distributed Practice: For Best Results, Spread Your Study over Time
  3. Elaborative Interrogation: Channel Your Inner Four-Year-Old
  4. Self-Explanation: How Do I Know?
  5. Interleaved Practice: Mixing Apples and Oranges
    自测,分散复习,自我审问和解释,混合练习。

High Leverage Practices
read more

  1. Making content explicit through explanation, modeling, representations, and examples
  2. Leading a whole-class discussion
  3. Eliciting and interpreting individual students’ thinking
  4. Establishing norms and routines for classroom discourse central to the subject-matter domain
  5. Recognizing particular common patterns of student thinking in a subject-matter domain
  6. Identifying and implementing an instructional response to common patterns of student thinking
  7. Teaching a lesson or segment of instruction
  8. Implementing organizational routines, procedures, and strategies to support a learning environment
  9. Setting up and managing small group work
  10. Engaging in strategic relationship-building conversations with students
  11. Setting long- and short-term learning goals for students referenced to external benchmarks
  12. Appraising, choosing, and modifying tasks and texts for a specific learning goal
  13. Designing a sequence of lessons toward a specific learning goal
  14. Selecting and using particular methods to check understanding and monitor student learning
  15. Composing, selecting, interpreting, and using information from methods of summative assessment
  16. Providing oral and written feedback to students on their work
  17. Communicating about a student with a parent or guardian
  18. Analyzing instruction for the purpose of improving
  19. Communicating with other professionals

References:
Ambrose, S. A., Bridges, M. W., DiPietro, M. Lovett, M. C., & Norman, M. K. (2010). How learning works: Seven research-based principles for smart teaching. San Francisco, CA: Jossey-Bass.
Chickering, A. W., & Gamson, Z. F. (1987, March). Seven principles for good practice in undergraduate education. American Association for Higher Education Bulletin, 39(7), 3-7.
Zull, J. E. (2002). The art of changing the brain: Enriching the practice of teaching by exploring the biology of learning. Sterling, VA: Stylus.
GLASER, R. (1995). Application and theory: Learning theory and the design of learning environments. Paper presented at the 23rd International Congress of Applied Psychology, July 17-22,1994, Madrid,Spain.
Duschl, R. A., & Osborne, J. (2002). Supporting and Promoting Argumentation Discourse in Science Education. Studies in Science Education. doi:10.1080/03057260208560187

Today I saw this in our main library when the staff cleanup the restroom.
Door with leg
What a cool leg the door has! The idea is simple, but the result is so good. Sometimes simple change can make a big difference.

There also some design confuses me. Here is a table with sharp edge on the top surface. I really cannot understand what this edge serves for beyound hurting my arms when typing on my laptop.
Sharp edge table

Another example of confusing design. I really don’t know witch controler can light a fire to the stove under my pot.
gas stove

Nowadays, the environment is becoming worse and worse. One basic reason is bad design. Our company design good batteries with low-cost but ignored how to recycle and reuse the waste batteries. Similarly, the white pollution, air and water pollution all failded to take environment pollution cost into concern. These industries are all good examples of bad design and are badly need to change.

Well, how to solve these problems and create better future? The answer is design zero pollution industry pipeline. Just like the nature design all kinds of lives, no waste at all. For example, how to make use of clean energy as power for travelling. When you taking whole process into concern, you will find the horse and cart is one example of good designs. Of course, we will not return to this old method of travelling, but we really should rethink this design.

It is not just product design or pipeline design. It is also a life design. On behavior researcher found a very simple and effective way to save energy– sending a letter of electric usage report comparing with neighborhood. After being told use more than twice electric than neighborhood, people tend to pay much attention to save energy. This is just how behavior science used to affect personal life styles.

Nowadays, people have learnt to make use clean energy such as wind, water,sun. Researchers are also trying to invent new technologies of producing and storing and converting these energy. We are going to and have to achieve no waste design in order to live a better life for long run on earth.

亲爱的老婆圣诞节快乐!

今天是12月25号,我离开家到美国访学刚好5个月整。这五个月我知道老婆特别辛苦,也受了不少委屈,不仅仅是因为我在地球的另一端,你没了往日的依靠,而是你还要担负着做不满周岁的宝宝的母亲的责任,以及家庭和工作的双重重担。

2013年2月12号,我们的宝宝然然出生了:)。由于长时间坐着哺乳,大腿血液流通不畅造成了局部组织坏死,你的大腿上留下了两块死斑。你修完产假已经快要放暑假了,我就劝你别去上班了,你说不能耽误工作,结果还是上班了。我知道你很有责任心,也不娇气,但是我还是心疼。

7月25号我出国访学,你送我到机场,当飞机起飞的那一刹那,我的心情很沉重,我知道你将担负起整个家庭的责任。婆媳关系本来就难处,但你却处理的很好,从没有跟妈拌过嘴。

QQ聊天时你经常跟我说头晕,我知道你睡眠不足。你经常要熬夜赶稿子,我嘴上说“不要把工作带到家里”,实际上是不想你熬夜,因为我知道你第二天还要早起,要坐两个小时的公交车才能到学校。以前在家里,一般都是我送你出门,你经常来不及在家吃早饭,到了包子铺,你拿了包子就走,我来结账,就是为了赶时间,不迟到。

11月4号下午爸突发脑出血,是你带爸及时去了医院救治,幸亏救治及时咱爸才保平安。当天晚上你守了爸一夜,端屎端尿,这些本来应该是我来做的。我跟妈说,桃子不仅是我的老婆,还是宝宝的妈妈,你们的儿媳,而且还做了本应该由我这个儿子做的事情,你就像对我这个儿子一样对待这个儿媳吧。我也因为你只顾忙着工作,忽略了家里,生过你的气,但是有什么办法呢,该做的总是要做的。但是我还是要说你,健康是第一重要的,下次体检一定要去,要抽出些时间锻炼身体。

祝老婆永远年轻、健康、漂亮!

爱你的老公
12月24日 圣诞夜
于佐治亚

中文

已读

小说类
红楼梦
天眼
一花一世界
佛本是道
神游
生命是什么

在读

史记
老子
庄子

未读

论语
孟子
易经
大学
孟子
冰鉴

佐治亚神游而作

雾云山
(起笔)
仙踪浩渺远云山
雾雨清濛锁玉颜
敢问天人何处去
携天月下了人间


雾云山
(收笔)
仙踪浩渺远人烟
雾雨清濛锁玉颜
挂月楼台空伫立
神游欲海了无边


雾云山
(有意无律)
仙踪飘渺雾云山
悟心空待百花岩
天月不知何处去
身化万千在人间


雾云山
(破笔)
敢问天师何所在
天宫莫去去人间

欲问天人何处在
天宫莫去去人间

欲问云梯何处在
天宫莫去在人间

挂月楼台空伫立
遥盼玉颜下凡间

拜问天人何处去
不在远山在人间

学问学问,有问耐学。问之而学之,学之而深问之。学而生问,问而新学。故无问则无学,无学则无问。问为学之始,学为问之门。

问天地之道,学万物之法。问宇宙之始,窥沧海之变。问处世之道,学入世之法。问世事之变,学为人之道。故有大问而后又大学,有大学而后有质问。

宝宝顽皮好动,喜欢探索新鲜事物,但是也经常会发生危险。因此家长需要时时刻刻看护宝宝,预防危险的发生,一旦有突发事件也需要能够准确的应对。

急救措施

0、呛到东西了
如果孩子突然猛烈咳嗽,可能是因为呛到东西。父母应立即看看孩子嘴里是否有东西。如果东西还没被孩子咽下,就让孩子赶紧吐出来。如果孩子无法自行把东西吐出来,就让孩子趴在自己的腿上,用手掌拍他的背部。不到1岁的孩子要让他趴在自己的前臂上,扶好头颈。
稍大的孩子,可让他站在身前,把你的拳头放在他的腹部和最下面的肋骨之间,猛力向内并向上用力。如果喉咙里的东西还是不出来,再重复背部的拍打。以5次背部拍打和5次正面推动为一个单元,反复进行。如还没有缓解,就叫救护车。在救护人员到达前,要不断重复急救动作,做最后的努力。

1、烫伤、烧伤
孩子一旦烫伤或者烧伤,要迅速将孩子受伤的部位放到凉水中,这样可以起到冷却作用,能够减轻伤处的肿胀程度。然后将伤口附近的衣服脱掉或剪开。如果衣服和伤口粘在了一起,不要动它,去医院让医生处理。如果伤口面积很大,就要用干净的保鲜膜或布把伤口盖起来,马上把孩子送去医院。

2、流鼻血了
让孩子坐下,头向前倾,使鼻血顺利流出来。然后让他用手捏住鼻子,用嘴呼吸。10分钟后,如果血还没有止住,就捏两次,每次10分钟。
止血后,把鼻子擦干净,告诉孩子不要说话,不要咳嗽,也不要擤鼻涕,以避免将刚刚凝固的血块弄碎。但如果血流不止,需去医院处理。

3、拉伤或扭伤
首先要用小毛巾包几块冰,冷敷局部10分钟,然后帮他们绑上绷带,不要做其他动作,尽量放松,不要加速血液流动,这样可以减轻青肿和淤血的程度。

4、触电
如果孩子触电后还没有脱离电源,你绝不可以碰他,第一件事情是切断电源。如果一时找不到开关,可以站在一个干燥的绝缘物体上(如一本厚厚的电话本或一摞报纸),把电源拉开。
检查孩子的呼吸,即使他已经失去知觉,但只要有呼吸就有很大希望救活。触电在人体表面留下的伤痕面积可能不大,但对孩子的内脏可能有伤害,因此不要随意挪动孩子,要立即叫救护车。

5、食物中毒
如果孩子误食了有毒物质,一定要叫救护车。在救护车到达之前,尽量用催吐方法,让孩子把吃下的有毒物吐出来,而且不要让孩子多做运动,加速血流。尽量将呕吐物或者吃的残留物保存,并带到医院化验。

以上摘自:突发事件,宝宝急救方法 _玩具-小梅 - 阿里巴巴博客

旅行中的应急措施

1、飞机上的耳鸣

症状:宝宝会抱怨耳朵疼,憋得慌,难受。不会说话的宝宝则会一边抓着自己的耳朵一边哭闹不止。

处理方法:会出现这些问题,全是因为飞机在起飞和登陆的时候气压搞的鬼。所以在飞机起飞和登陆的时候,让小宝宝用奶瓶喝点水,或让他吃些东西。咽水和咽食物的过程,可以缓解气压给宝宝耳朵带来的痛苦。如果你也感到不适,就嚼一嚼口香糖。如果这些方法还不能让宝宝舒服,那就要使出必杀术:捏住宝宝的鼻孔,让他咽口水。

2、晕车

症状:头晕、恶心、呕吐、头疼、出很多汗、脸色苍白、流口水或口水增多、不爱睡觉。

处理方法:如果你们是乘汽车旅行,那就马上把车停在路边最近的休息区,让宝宝下车呼吸一些新鲜空气。如果你们正在飞机上,请空中小姐尽可能给宝宝安排一个靠近机翼的位置坐下。如果你们乘船旅行,马上把宝宝抱到甲板上,尽量让他向正前方的海平线看。另外,喝点煮熟的姜水对治疗晕车也很有帮助。

3、腹泻
症状:突然的腹泻会把你和宝宝弄得不知所措,通常一天会有5~6次,都是水样的便便。

处理方法:宝宝总会在旅途中出现腹泻,可能是因为生活习惯改变,可能是大家常说的水土不服,严重一点的是因为感染了某些细菌。不必着急,大多数情况只要护理好了很快会痊愈。这时候你先要给孩子补充一些电解质溶液,防止宝宝出现脱水症。饮食上要多给孩子吃一些清淡的食物。随身携带的止泻药这时候也该登场了。如果宝宝的腹泻持续三天还没见好转,或者他还伴有呕吐、大便出血等症状,就要马上和医生联系。

如何预防:如果你们是在外野营,要保证你们的食物必须是新鲜的,制作的时候一定要煮熟。如果是到外地旅游,最好给宝宝喝瓶装水。

Tips:旅行急救箱

做好了旅行安全计划、学习了突发事件的处理方法,别忘了把你的急救箱带上,一旦遇到突发事件,只有它才能让你满腹的论理变成帮助宝宝的法宝。下面这些东西是常用的急救用品只是一个参考,你在为宝宝准备时,还要根据宝宝的具体情况,带上一些他需要的物品。
  1.绑带,纱布,创可贴
  2.消毒纸巾
  3.退烧药水
  4.退热贴
  5.剪刀、镊子
  6.治疗割伤的药膏
  7.体温计
  8.消毒药水
  9.电解液

以上摘自:宝宝旅行遇突发事件如何处理_39健康网_育儿

生活中的应急措施

1、被刺扎了
应急方法 :如果孩子皮肤表面扎了刺,可以用胶带粘住小刺,然后把刺拽出来。如果刺比较大,或者扎进皮肤较深,最好用镊子把刺拔出来。
方法分析 :刺会粘到胶带上,这样拔刺不但快而且操作起来比较简单。就医指征 如果出现下面的几种情况,最好联系医生:你没办法把刺取出来,扎刺的地方发红、有感染的迹象,或者孩子感到非常痛等。

2、蛰伤
应急方法 : 马上用信用卡边或比较钝的刀刮去动物的蛰刺,然后用肥皂水仔细清洗,最后拿一块冰敷在伤口上。
方法分析 : 用刮的办法而不是用手指拔去动物的蛰刺,可以避免动物毒液进入孩子的皮肤,敷冰可以防止浮肿及疼痛。
就医指征 : 如果孩子出现过敏反应、呼吸困难、嘴和脖子周围开始肿胀,或者在伤口周围出现皮疹时应该马上去医院。

3、堵塞的鼻孔
应急方法 :在温水中溶解小半勺食盐,然后将溶解后的液体装在小的喷雾器内,在每个鼻孔喷两下,然后让孩子用纸巾擤鼻涕(假如孩子太小,还不懂得怎样擤鼻涕,可以用吸鼻器替孩子吸出鼻子内的脏物)。
方法分析 :盐水可以软化浓稠的鼻涕,使之容易被擤出或吸出,同时有助于补充鼻黏膜的水分。
就医指征 :如果怀疑孩子的症状为耳朵或鼻窦感染就需要去医院了。其症状为发烧、持续不断地咳嗽、耳朵疼、或者鼻孔出现黄色或绿色的分泌物。

以上摘自:宝宝突发事件应急方法_育教知识_星宝宝育教网

及其特殊的情况

如果你的孩子在冬天用舌头舔了冰凉的金属杆……

宝宝总是像一只顽皮的小狗,喜欢用他们的嘴去检验他们觉得有兴趣的东西。假如冬日户外出游的时候,宝贝趁你不备伸,出小舌头舔了一下某个金属栅栏,那么,糟糕的事 情就会发生了!

“舌头上的唾液会在冰冷的金属杆上结晶,可怜的小舌头就会粘在金属杆上。”密歇根儿童医院急诊部的主任Stephen Knazik告诫父母,“这时候,千万要固定住宝宝的头, 万不可以让他任意晃动,这样他会将舌头的表层组织撕扯下来,造成流血和肌肉的损伤。这时候,你要赶紧找来温水(过热会烫伤,过冷效果不明显),浇在宝宝舌头和金属杆粘住的部位,使冰晶融化,它们就能够分开了。”

以上摘自:如何科学处理宝宝突发事件_儿童急救_中国健康网