sign test
LMS Test Lab中文操作指南 Signature信 特征测试分析
LMS b中文操作指南— Signature信号特征测试分析比利时LMS国际公司北京代表处2009年2月LMS b中文操作指南— Signature信号特征测试分析目录---开启软件--- (2)第一步，通道设置(Channel Setup) (4)第二步，校准灵敏度(Calibration)—选做项 (8)第三步，跟踪设定(Tracking Setup) (9)第四步，示波/采集设定(Acquisition Setup) (14)第五步，在线分析设定(Online Processing) (17)第六步，开始测量(Measure) (20)第七步，频域后处理(Post Processing) (23)第八步，时域信号选择(Time Data Selection ) (24)第九步，时域信号后处理(Time Data Processing ) (24)---开启软件---1- 在 Windows 桌面上点击 Test Lab的快捷方式，然后点击进入b Signature文件夹，在快捷方式里选择打开 Signature Acquisition （只是采集，无后处理功能）或Signature testing (根据购买协议，有高级版和标准版之分，主体内容2者一致，都有Post processing频域后处理功能，高级版则多了时域信号后处理功能（time data processing）). 图标见下图:2- 下面以Signature Testing – Advanced 为例说明 Signature testing的操作说明，点击打开后出现软件界面如下：3- 开始软件操作，打开项目a) 点击 File键正下方的空白项目图标，新建一个软件默认空白设置的项目（Newproject）;b) 也可以点击 File键，在下拉菜单里选择 New，弹出选择项目模板的界面如下在模板列表中选择点击一个以前存好的或者软件默认提供的模板（后缀为.tpl），然后点击Open打开一个新的项目，打开的新项目将套用模板里所有的设置（包括通道设置，采样频率，加什么窗函数等各种设置）；c) 当然也可以点击图标来打开以前已经存在硬盘里的项目文件(后缀为.lms，路径在安装 Test Lab软件时已设定，存数据的文件夹叫LMSLocal9A（9A是版本号，如果8A 的话就是LMSLocal8A）路径假设设定成 E:\LMSLocal9A\，那么格式为*.lms的项目文件和与*同名的文件夹（存有全程时域信号Time date的TDF格式文件）存在路径E:\LMSLocal9A\电脑用户名\Data下)。
ic设计中signon signoff
在IC设计中，signoff指的是成功完成IC设计的所有检查的一个标志。
它通常发生在设计完成后，用于确认设计数据已经达到交付标准。
在signoff过程中，会进行一系列的检查和验证，以确保设计的正确性和可靠性。
具体来说，signoff包括以下方面：
1. 功能仿真：在设计的电路进入布局布线前，应检查其功能是否符合设计要求。
2. 时序仿真：设计经过布局布线之后，使用EDA工具进行寄生参数提取，形成精确的post-layout电路网表，对此网表做时序仿真，来检查时序行为是否符合要求。
完成这些步骤后，就可以进入foundry流片生产。
因此，signoff 分析做的是否完整和完备对IC产品的质量是至关重要的。
若在这个阶段查找到问题并加以修正要比在生产阶段的花费要低廉很多，所以各个IC公司都非常重视这个过程，EDA厂商也都有自己完整的用来做sign-off的工具集。
以上信息仅供参考，如有需要，建议咨询专业技术人员。
test函数的用法
test函数的用法1. 单元测试：test函数可以用来进行单元测试，即对程序的最小单元进行测试。
在编写单元测试时，我们可以为每个函数或方法编写一个对应的test函数，用于验证函数在各种输入情况下的返回结果是否符合预期。
例如，假设我们有一个计算器程序，其中有一个add函数用于实现两个数的加法。
我们可以编写一个test_add函数，通过传入不同的参数进行测试，然后判断返回结果是否与预期相符。
2. 集成测试：test函数还可以用于进行集成测试，即对程序的多个模块或组件进行整体测试。
在集成测试中，我们可以调用各个模块的函数，并根据预期输出结果进行断言，判断整个程序的协调性和正确性。
3. 性能测试：test函数还可以用于进行性能测试，即测试程序在大数据量或高并发情况下的性能表现。
通过模拟实际运行环境和负载情况，可以对程序的性能进行评估和优化。
例如，我们可以编写一个test_performance函数，在测试环境中模拟大量数据或并发请求，然后计算程序的响应时间和吞吐量等指标，并与预期性能目标进行比较。
4. 边界测试：test函数还可以用于进行边界测试，即测试程序在边界值情况下的行为是否符合预期。
边界测试可以帮助我们找到程序可能存在的边界条件错误或异常情况。
例如，假设我们有一个函数用于计算一个数的阶乘，我们可以编写一个test_boundary函数，分别测试输入为0、1和100等边界值的情况，然后验证返回结果是否符合预期。
5. 异常测试：test函数还可以用于进行异常测试，即测试程序在异常情况下是否能够正确处理异常。
通过模拟各种异常场景，可以验证程序的健壮性和容错性。
例如，我们可以编写一个test_exception函数，测试在输入非法参数时，程序是否能够正确抛出异常或返回预期的错误码。
另外，test函数还可以与自动化测试框架结合使用，例如JUnit、pytest、Selenium等。
这些测试框架提供了更加便捷和强大的测试工具和断言机制，能够大大简化测试代码的编写和执行。
sign解密参数
sign解密参数
在解决sign解密参数的问题时，需要遵循一些步骤。
首先，需要打开目标
网站，进行模拟登录，然后使用快捷键fn+f12打开调试界面。
接下来，定
位到json的原始地址，对指定页面的json进行参数分析。
在这个过程中，可能会发现参数sign值为加密，其长度为32位，初步怀疑为md5加密。
一旦确定了加密的参数，可以进行断点调试。
具体来说，需要确定需要还原的加密值sign，然后根据发送get请求发起的params参数，进行参数js
参数定位。
最后确定到加密的js地址后，对js代码打上断点，关注入参和
出参，进行调试。
在这个过程中，如果怀疑sign值生成和MD5算法有关联，可以将加密的
值通过md5加密查看结果。
如果分析结果和js调试的sign值一致，那么
接下来可以进行算法还原。
在算法还原的过程中，可以查看原始的url地址，并确定js调试的sign值
和请求的url的sign值一致。
然后，将所有的js算法还原成python代码。
最后，通过对比入参和出参是否与结果值一致，可以确定解密参数的过程是否成功。
需要注意的是，这个过程涉及到一些复杂的操作和专业知识，需要具备一定的编程基础和网络安全意识。
同时，也要注意遵守法律法规和网站的使用协议，不要使用非法手段获取他人的敏感信息。
监考须知-中文版
▶ During the reading test
阅读考试中 如有缺考人员，在考生员名单缺考栏（ ABSENT）填“O”。Circle
on the "ABSENT" on an
examinee's roster if an applicant is absent
Signatures of two proctors 2人签名
10. Distribute the test paper to each applicant
11. 문제지 배부 发放试卷
잔여 문제지 = 결시자 수
到开考前5分钟 (10点25分) 试卷发放完毕。
Distributing test papers until five minutes before the test. (10:25 or 15:25)
阅读考试开始
1名监考教师在教师前面。
One proctor monitor at the front, while the other will monitor at the back
1名监考教师核对考生相貌、身份证、考场信息表和准考证
One proctor has to verify each applicant by confirming their face and personal data, based on the roster and Passport.
考试过程中携带或使用手机，都按违纪处理。
Applicants are not allowed to bring cell phone.
考试过程中携带或使用手机，都按 违纪处理。.
Examinee who have or use the mobile phone shall be regarded as cheater. Register as a cheater 부정행위 처리!!
双样本假设检验
（2）如果样本采用两点记分，可以用McNemar检验
（3）如果样本采用等级记分，可以用SIGN检验 一般认为，Wilcoxon检验的精度比SIGN的精度高，对原始数据的变化
的敏感性更强。如果样本数据为等级记分时，建议使用Wilcoxon 和SIGN检
验，如果样本数据为连续数据时，建议使用Wilcoxon检验。
曼惠特尼u检验mannwhitneytestks双样本检验kolmgorovsmirnovtest摩西极端反应检验mosesextremereactiontestww游程检验woldwolfowitzrunstest变量观测值要一一对应注意分组变量的设定技巧双样本假设检验双样本假设检验一两个相关样本t检验又叫配对样本t检验用于检验两个相关的样本是否来自具有相同均值的总体
Ranks
事前
事后
等级差
N AFTER - FIRST Negative Ranks Positive Ranks Ties Total 4a 6b 0c 10
1
2 3 4 5
2
4 1 8 6
+1
+2 -2 +6 +1
Mean Rank 7.25 4.33
Sum of Ranks 29.00 26.00
双样本假设检验
四、两个相关样本Sign检验
通过二项分布来检验两个样本所属的总体数据分布差异的显著性。属于两 个相关样本非参数检验。又称作配对符号检验。
Frequencies N AFTER - FIRST Negative Differencesa b Positive Differences Tiesc Total 4 6 0 10
九、W—W游程检验
是单样本游程检验的推广。适用于双值型变量。通过两组数据变化的随机 性考察其总体数据随机分析的差异性。
hutool secureutil.sign 加签验签基本用法
hutool secureutil.sign 加签验签基本用法一、简介Hutool是一套Java工具包，提供了许多常用的功能，包括安全相关的功能。
SecureUtil是Hutool工具包中的一个类，提供了加签和验签的功能。
sign方法是用于对数据进行加签的操作，verify方法是用于对数据进行验签的操作。
二、基本用法1. 加签加签是将数据与秘钥进行运算，生成一个签名。
具体步骤如下：a. 获取SecureUtil对象。
b. 使用秘钥初始化SecureUtil对象。
c. 使用sign方法，传入需要加签的数据和秘钥，即可得到签名结果。
示例代码：```java// 创建SecureUtil对象SecureUtil secureUtil = new SecureUtil();// 初始化SecureUtil对象，使用秘钥secureUtil.init("your secret key");// 对数据进行加签String data = "需要加签的数据";String signature = secureUtil.sign(data);```2. 验签验签是对已经加签的数据和秘钥进行运算，验证签名是否正确。
具体步骤如下：a. 获取SecureUtil对象。
b. 使用秘钥初始化SecureUtil对象。
c. 使用verify方法，传入需要验签的数据、签名和秘钥，即可得到验证结果。
示例代码：```java// 创建SecureUtil对象SecureUtil secureUtil = new SecureUtil();// 初始化SecureUtil对象，使用秘钥secureUtil.init("your secret key");// 对数据进行加签和保存签名结果String data = "需要验签的数据";String signature = secureUtil.sign(data);String dataSignature = secureUtil.sign(data); // 可以得到原数据的签名结果，用于比较验签结果是否正确// 进行验签boolean isValid = secureUtil.verify(data, signature); // 如果返回true，则签名正确；否则签名错误。
sign校验规则
sign校验规则
1.签名字符串必须按照特定格式组成，包括请求参数和密钥等信息。
2. 请求参数必须根据参数名称按字典序排序，并且不包含空值
或者签名参数本身。
3. 签名算法必须和服务器端约定的一致，常见的有MD5、SHA1等。
4. 签名密钥必须妥善保管，不能泄露。
5. 签名过程中必须排除掉请求参数中的空值或者签名参数本身。
6. 如果请求参数中包含中文字符，必须先进行编码再进行签名。
7. 签名结果必须与服务器端生成的一致才能认为请求合法。
8. 签名过程中必须考虑并处理请求参数中的特殊字符和特殊情况。
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骨科基础丨史上最全的50种骨科检查方法，骨科医生必收藏！
骨科基础丨史上最全的50种骨科检查方法，骨科医生必收藏！医生通过体格检查，发现和辨别正常所见和有临床意义的体征，进行疾病的初步诊断。
体格检查是医生的基本功，特别是骨科专科检查。
正确查体，对于准确诊断非常重要。
骨科专科检查更是每个医师的必备技能，无论是日常临床工作还是各种职称考试都是重点。
1前屈旋颈试验 Fenz sign先令患者头颈部前屈，再左右旋转活动，若颈椎处出现疼痛即为阳性，提示颈椎骨关节病，表明颈椎小关节多有退行性病变。
2椎间孔挤压试验 Spurling sign患者头转向患侧并稍屈曲，检查者左手掌置于患者头顶，右手轻叩击掌背。
当患肢出现放射性疼痛或麻木感时，即为阳性。
提示有神经根性损害，见于神经根型颈椎病。
3颈脊神经根张力试验（Eaten sign 或 Lasequard sign）：患者坐位，检查者一手将患者头部推向健侧，另一手握住患者腕部并向下牵引，如出现患肢的麻木疼痛即为阳性。
提示神经根型颈椎病、臂丛损伤或前斜角肌综合征。
4Addsion sign 试验患者坐位，仰首转向患侧，深吸气后屏住呼吸，检查者一手抵住患者下颌，一手摸患侧桡动脉，动脉搏动减弱或消失则为阳性。
提示血管受挤压，常见于前斜角肌综合征。
5Thomas sign 试验患者仰卧，大腿伸直，则腰部前凸；屈曲健侧髋、膝关节，迫使脊柱代偿性前凸消失，则患侧大腿被迫抬起，不能接触床面，即为阳性。
常见于腰椎、骶髂关节及髋关节内有病变，或内收肌痉挛。
6直腿抬高试验 Lasegue sign患者仰卧，检查者一手握住患侧足跟，另一手保持膝关节伸直，抬高患肢至患者疼痛，并记录其角度，在60~70度出现坐骨神经的放射性疼为阳性。
7Bragard sign 加强试验在Lasegue ( )时，缓慢放低患肢高度，待放射性痛消失后再将踝关节被动屈曲，如再度出现放射性疼痛，即为阳性。
此二征阳性为腰椎间盘突出症的主要诊断依据。
8Arid test 试验患者坐立于床边，双小腿下垂，分别抬高小腿，观察出现疼痛和麻木时小腿高度和膝关节屈曲角度，结果同lasegue。
新泽西NJ驾照模拟试题road signs practice test
This is a 'U-Turn Only' road sign.TrueFalse okThis sign means that u-turns are permitted from this lane. However, it doesn't have 'u-turns only' restriction and the driver can proceed straight ahead or make a u-turn.01.This sign indicates:trucks entering a highway okhigh occupancy vehicles entering a highwaydangerous goods vehicles crossing a highwayno entry for trucksThis sign indicates trucks entering or crossing the highway ahead. Drivers must slow down and watch for trucks.02.What does this sign indicate?Vehicles may cross the broken yellow line to pass or turn, if it is safe to do so okVehicles are not allowed to cross the broken yellow line to pass or turnVehicles are allowed to cross the broken yellow line only to turn, if it is safe to do soVehicles are not allowed to cross the broken yellow line under any circumstancesDrivers must drive to the right of the broken yellow centerline. When it is safe, they may cross this line to turn or pass another vehicle.03.What does this sign mean?Traffic must merge rightTraffic must merge leftTraffic must make a right turn onlyTraffic must make a left turn only okThis is a traffic regulatory sign. This sign indicates that the traffic must make a left turn only.04.What does this flashing yellow light indicate?Drivers must increase their speed and clear the intersectionDrivers must stop at the signDrivers must slow down and proceed with caution okDrivers must make a turn at the signA flashing yellow traffic light means that drivers must slow down, check for cross-traffic, and proceed with caution.05.This sign with the number '95' represents:the number of miles to the next exitthe exit numberthe maximum speed allowed on a highwaythe interstate highway number okThis sign represents the interstate highway route number 95.06.What does this figure indicate?A broken white line that allows passing okA car making a 'U' turnAn accident situation due to a less following distanceA broken white line that prohibits passingThis sign means that a broken or dashed white line allows the passing of a vehicle on the left.07.What does this sign mean?Do not take a left turnThis side of the road is temporarily closedDo not take a right turn okDo not mergeThis sign prohibits drivers from making a right turn. These signs tell you where you can go and where you can turn, often using an arrow symbol. These signs can be located on the side of the road or hanging over the lane of travel. Sometimes arrows are painted on the road as a supplement to the sign.08.This sign may be used to:inform drivers to make a U-turnwarn drivers of a one-way aheadinform drivers of a school zoneguide drivers into certain traffic lanes okFlashing arrow panels may be used in work zones to guide drivers into certain traffic lanes and to inform them that part of the road ahead is closed.09.What does this red octagonal sign indicate?A one-way signA no-entry signA stop sign okA yield signThis is a regulatory sign. You must stop near the sign and yield the right-of-way to other vehicles.10.What does this sign mean?A fuel filling station is aheadA hospital service is aheadA rest area is aheadA phone service is available ahead okThis sign is a service sign. It indicates that a phone service is available ahead.11.These signs located on freeways are called:work zone markersdynamic message signs okcrossroads indicatorsroute marker signsDynamic message signs provide important information to travelers. Messages can be changed to reflect the current conditions, route traffic, construction schedules, incidents, etc.12.What does this traffic sign mean?You may go straight ahead okOnly passenger vehicles are allowed to go straightYou are not allowed to go straightYou must stop before going straightA green arrow pointed upward means you may go straight ahead.13.What does this signal mean?Traffic island aheadTraffic must proceed with caution okTraffic must go without stoppingTraffic must come to a complete stopThis is a flashing yellow signal. Traffic must proceed with caution. Yield to vehicles and pedestrians, and proceed when it is safe.14.This diamond-shaped sign means that:a median is aheadthe road ahead has a dipthe road ahead has a bump oka hill grade is aheadThis sign indicates a bump in the road ahead. Slow down to avoid loss of control.15.What does this circular arrow sign mean?There is a roundabout ahead; prepare to yield to traffic okThere is a one-way road ahead; proceed with cautionA U-turn is permitted; go slowThere is a traffic merging area ahead; stop before mergingThis sign means that there is a roundabout (circular intersection) ahead. Drivers must slow down and prepare to yield to traffic in the roundabout.16.What does this road sign represent?Divided highway ends okMerge rightOne-way aheadKeep to the right of divided highwayThis sign indicates that the divided highway ends; traffic travels in both directions on the same road ahead. Keep to the right.17.What does this sign indicate?Vehicles merging ahead; do not increase the speed to 45 mphDrive with a speed of 45 mphA speed zone ahead; be prepared to reduce the speed to 45 mph okConstruction ahead; reduce your speed to 45 mphThe larger sign tells you that a speed zone is ahead. The smaller sign indicates what the speed limit will be.18.This sign indicates:a winding roada right curvea sharp right turn oka one-wayThis sign indicates that a sharp right turn is ahead. Drivers must slow down and be alert.19.What is the meaning of this sign?Gravel on the roadRoad is slippery and wetConcealed roadRoad shoulder is much lower than the road surface okThe sign shown here indicates to the driver that the road shoulder is much lower than the road surface.20.You can drive in a lane marked with this sign if:you are riding a bicycle only. okare riding a motorcycle.you are passing the vehicle in front of you.you are carrying two or more people.You can drive in a lane marked with this sign if you are riding a bicycle. This sign marks bicycle lanes.21.This arrow-marked sign warns of:a narrow road aheada sharp curve aheada winding road ahead oka median aheadThis sign warns of a winding road ahead. The road at the sign has more curves; drivers must go slow.22.This posted sign is a/an:speed indicator on highways okinterstate route markerspeed indicator at rotarieshill area speed limit signThis sign indicates the maximum safe speed allowed in ideal driving conditions on highways. 23.What does this traffic sign mean?Construction ahead after 1000 ftBeginning of an alternate road okParking zone aheadRight turn is prohibited after 1000 ftThis sign indicates that there is a road closure ahead, but there is an alternate route in 1000 feet.24.At 9:30am, beside this sign you are :not permitted to park. okallowed to park with a special permit only.allowed to park for less than 5 minutes.allowed to park.At 9:30am, beside this sign you are not permitted to park. You cannot park between the hours that are posted on the sign.25.When can you drive in a lane marked with this sign?If you are driving a vanIf you are riding a motorcycleIf there are two or more people in your vehicle okIf your vehicle is full of people26.If you'd like to turn right at an intersection with this sign:you are not permitted to turn right at this intersection.you must stop and then proceed with caution.you must wait for a green light. okyou can turn as long as no one is coming.If you'd like to turn right at an intersection with this sign you must wait for a green light to turn.27.This special traffic signal directs the driver to:make a left turnstopmake a right turn okgo straightThis five-section head signal is used to regulate right turns at intersections. The turning traffic has a protected right turn, meaning all oncoming or conflicting traffic is stopped.28.This sign indicates:the interstate highway number okthe distance to the nearest exitthe exit numberthe interstate highway speed limitTraffic guidance signs provide drivers with information about the type of road they are traveling, upcoming highway entrances and exits, and distances to various destinations. This sign indicates the interstate highway 70.29.This sign on a highway shows:a railroad crossing aheadan upcoming side road okan upcoming three-way stopa limited-access side roadThis sign shows an upcoming side road. You must look for other vehicles entering from that direction.This sign means:you must stop at rail tracks.you are permitted to drive on the rail tracks.railroad crossing up ahead.do not drive on railroad tracks. okThis sign means that you are not permitted to drive on the railroad tracks.What does this arrow-marked sign mean?You are approaching a left turnA sharp U-turn aheadYou are approaching a right turn okA sharp left turn aheadThis supplemental arrow on the route marker assembly means you are approaching a right turn to continue on that certain route.This image indicates:vehicles must not cross the solid yellow line, except to passvehicles must not cross the dashed white line under any circumstancesvehicles must not cross the solid yellow line oknone of the aboveYellow line markings separate multiple lanes of traffic going in opposite directions. Drivers should not cross solid yellow line.The broken yellow lines on the pavement mean:Traffic moves only in one directionPassing is allowed if done safely okThe left lane is used for bicycles and motorcyclistsNo passing allowedBroken yellow lines indicate that passing is allowed only when it can be done safely.You can drive in a lane marked with this sign if:you are passing the vehicle in front of you.you are carrying two or more people.are riding a motorcycle.you are riding a bicycle only. okYou can drive in a lane marked with this sign if you are riding a bicycle. This sign marks bicycle lanes.ADVERTISEMENT This arrow sign means:merge leftgo straightturn left or go straight okdo not turn left or go straightThis sign regulates traffic and directs the driver to turn left or go straight.This reflective orange triangle sign represents:A heavy truckA sign for fast-moving vehiclesA dangerous goods-carrying vehicleA sign for slow-moving vehicle okA reflective orange triangle sign is placed on the rear of a vehicle that travels at speeds less than 25 mph.The driver's arm position in the image indicates that:The car is in trouble and needs helpThe car is making a U-turnThe car is slowing or stopping okThe car is making a right turnThe driver's arm position indicates that the car is about to slow or stop.ADVERTISEMENT What does this sign mean?A hospital aheadA handicapped crossing ahead okPedestrians crossing aheadHandicapped parking aheadThe sign indicates a handicapped crossing ahead. Drivers must reduce their speed and proceed with caution. What does this figure indicate?A broken white line that prohibits passingAn accident situation due to a less following distanceA broken white line that allows passing okA car making a 'U' turnThis sign means that a broken or dashed white line allows the passing of a vehicle on the left. What does this regulatory sign mean?No U-turns allowedMust make a right turnDo not merge leftNo left turns allowed okThis traffic regulatory sign indicates that no left turn is allowed on the way.This service sign indicates:parking service is availableaccommodation is available okhospital service is availableamenities are availableThis is a service sign. Drivers are advised to use accommodation facilities, if needed. What does this sign mean?An acceleration ramp near a freeway; drivers must merge with freeway trafficA bump ahead; drivers must maintain a uniform speedA steep hill ahead; drivers must shift to a lower gear okA narrow passage near a hill; drivers must go slowlyThis sign warns drivers of a steep hill ahead. Drivers may need to slow down at the top or change to a lower gear.If you see this sign, you:can only stop to take a break.must park on the left of the sign.should not park on the left of the sign. okcannot park in the area.If you see this sign, you should not park on the left of the sign. You are permitted to park on the right.What does this sign indicate?Detour aheadKeep to the right of the traffic island okDivided highway endsTurn right for low-clearance underpassThis sign indicates that the street or a highway is divided by an island and approaching vehicles must keep to the right.This sign with the number '95' represents:the maximum speed allowed on a highwaythe exit numberthe number of miles to the next exitthe interstate highway number okThis sign represents the interstate highway route number 95.What does this sign mean?Road turns ahead; slow to a safe speed okNarrow bridge ahead; go slowRight lane exits buses exceptedMerging traffic ahead; stop and proceedThe road ahead sharply changes direction. Drivers must slow down to a safe speed.What does the arrow mark sign mean?Directional arrow okRest area open to the rightGo straightPrepare to stopThis is a directional arrow sign.These pavement markings mean:vehicles traveling in both directions can take left turns okA three-way roadvehicles traveling in both directions can take right turnsA one-way roadThese center lanes are reserved for making left turns (or U-turns, when they are permitted), but can be used by vehicles traveling in both directions. On the pavement, left-turn arrows for traffic in one direction alternate with left-turn arrows for traffic coming from the other direction. These lanes are marked on each side by solid and dashed yellow lines.What does this figure mean?Crew at work; vehicles must slow downA flag person ahead; go slowA school crossing ahead; vehicles must stopA pedestrian crossing ahead; vehicles must yield okThis figure means that a pedestrian crosswalk is ahead. Drivers must yield to pedestrians.What does the following sign from the driver indicate?The driver wants to make a U-turn.The driver is signalling to take a left turnThe driver signalling to take a right turn ok The driver wants to pass your vehicleThe driver is signalling to make a right turn.。
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第三步：符号检验（Sign Test）
由于 S , S ~ Biu(n,1 / 2) ，则用两种方法求其p值
方法二：正态性修正
K n / 2 0.5 n / 4
> tt=(sum(x>57)-length(x)/2+0.5)/sqrt(length(x)/4) -2.25 > pnorm(tt)*2 0.02444895
符 号 检 验
（1）对总体中位数提出假设 （2）统计量 K =min{ S + , S- } ( b(n,0.5)) （3）求p值进行推断
K n / 2 C N (0,1) n / 4
【实验背景】 假设武汉市16座预出售的楼盘均价（单位：百 元/平方米）如表
t
X 0 S/ n
第二步：t 检验
用两种方法，计算 t 检验法的p值 • 直接调用t.test命令 > t.test(x-57)
One Sample t-test data: x - 57 P-value > 0.05 t = -0.1412, df = 15, p-value = 0.8896 alternative hypothesis: true mean is not equal to 0 95 percent confidence interval: 结论：不能拒绝零假设。 -8.045853 7.045853 sample estimates: mean of x -0.5
第三步：符号检验（Sign Test）
不论用何种方法求p值，都有 p-value < 0.05 结论：拒绝零假设，认为数据的中心位置与每平方 米5700元存在显著差异。 两种检验方法得到了看似相反的结论，到底哪一种 结果才是对的呢？
结果分析
首先要明确仅从两种方法的结论上来比较显然是不 恰当的，原因是两种方法采取的假设陈述本身就不一 样，一个是均值，一个是中位数考虑，这表示我们对 问题的理解角度是不同的，不同的理解完全有可能导 致不同的结论。 在t检验中，结论是不能拒绝零假设，它并不表示 接受零假设，它仅仅说明要拒绝零假设还需要收集更 多的证据。 t检验是在假设了正态的总体的前提下得到得到了 不可靠的结果。t检验没有成功的原因是分布假定不 适当，于是我们有理由认为t检验在这里是不合适的。 符号检验的结果较t检验的结果更可信。
> hist(x) #直方图 > qqnorm(x) #正态Q-Q图 > qqline(xk normality test data: x W = 0.5691, p-value = 8.388e-06 P值较小，故而不是来自正态分布。 从上图可看出，很可能不是正态分布，是否确实如此呢？ 可以用Shapiro-Wilk检验来作正态性检验。 > shapiro.test(x) #备择假设：不是正态分布
【实验结束语】
在非正态总体前提下，使用正态分布的检验方法 一般是不适当的，此时需要借助非参数统计，在非 正态总体时，非参数统计方法具有较好的稳健性， 同时有较广泛的适用性。 对非对称分布，由描述统计的结果可知，中位数 较均值而言是对总体中心位置更稳健的估计。
【思考】
如果中位数是对称中心，符号检验方法能否可以用？ 所得的结论是否可信？
非参数统计实验
符号检验
主讲：蒋锋 PhD
中南财经政法大学统计与数学学院
符号检验
一、实验目的及要求 二、实验环境 三、实验原理
四、实验设计及知识回顾 五、实验过程
六、实验结束语
【实验目的和要求】
掌握 t 检验法与符号检验，注意其区别 掌握单一样本中位数检验的符号检验法，并 会应用正态性修正 会用R语言对建立的数据进行分析，并会编 制符号检验法的R程序
用R求检验统计量 > sum(x>57) [1] 3 > sum(x<57) [1] 13
S , S
第三步：符号检验（Sign Test）
由于 S , S ~ Biu(n,1 / 2) ，则用两种方法求其p值
方法一：二项分布 > binom.test(sum(x>57),length(x),0.5) or binom.test(sum(x<57),length(x),0.5)
Exact binomial test 方法二：正态性修正 data: sum(x > 57) and length(x) number of successes = 3, number of trials = 16, p-value = 0.02127 alternative hypothesis: true probability of success is not equal to 0.5 95 percent confidence interval: 0.04047373 0.45645655 sample estimates: probability of success 0.1875
【实验环境】
R软件
【实验原理】 非参数统计方法具有较好的稳健性，同时有较广 泛的适用性。对非对称分布，由描述统计的结果 可知，中位数较均值而言是对总体中心位置更稳 健的估计。
符号检验（Sign Test）是利用正、负号的数目对 某种假设作出判定的非参数统计方法。当原假设 为真（H 0 : M M 0）时，大于 M 0的数据个数 S 与 小于 M 0的数据个数 S 应该很接近；如果两者相 差太远，就有理由拒绝原假设。
第二步：t 检验
假设检验问题：
H0 : 57
H1 : 57
用R计算其样本均值、样本方差、样本标准差、中位 数, 比较中位数与均值是否一样
> mean(x) [1] 56.5 > var(x) [1] 200.5333 > sd(x) [1] 14.16098 > median(x)
问：该地区平均楼盘价格是否与媒体公布的57 （百元/平方米）的说法相符？
【实验过程】
同学们请分组进行以下实验操作： 实验软件：R软件 检验方法：t 检验 符号检验 正态性修正
第一步：统计图 ① 进入R控制台，在R Console中输入16座预出售 的楼盘均价数据
>x=c(56,52,51,45,48,56,60,52,61,46,55,55,52,107,53 ,55) ② 作直方图和qq图，初步判断是否是正态分布
【实验设计及知识回顾】
统计量计算 t检验法 数据 录入 统计图
符号检验法 二项分布
确定检验的问题 假定分布结构
决 策
找原因
【回顾理论知识】
（1）对总体均值提出假设（单边或双边） （2）构造统计量 X 0 检 t ( t (n 1)) 验 S/ n
正态性修正
t
（3）求p值进行推断
• 通过p值定义计算
> t=(mean(x)-57)/(sd(x)/sqrt(length(x)))#求统计值 > t -0.1412332 > pt(-0.1412332,15)*2#求p值 [1] 0.889565
第三步：符号检验（Sign Test）
假设检验问题：
H0 : M M0 57; H1 : M M0