问题如下图：
老师 不太懂解释中那个chi square数是什么 怎么来的 麻烦讲解一下哈 谢谢啦
选项：
A. 
B. 
C. 
D. 
解释：
菲菲_品职助教 · 2018年11月30日
同学你好，
卡方分布的统计量有相应的计算公式。
卡方分布的临界值是通过查卡方分布临界值表得出来的。表中所给值直接只能查单侧概率值，可以变化一下来查双侧概率值。例如本题，要在自由度为24的卡方分布中，得到双侧概率为0.05所对应的上下端点可以这样来考虑：双侧概率指的是在上端和下端各划出概率相等的一部分，两概率之和为给定的概率值，这里是0.05，因此实际上上端点以上的概率为0.05/2=0.025，用概率0.025查表得上端点的值为39.36。下端点以下的概率也为0.025，因此可以用0.975查得下端点为12.4。通过卡方分布统计量的计算公式，我们求得该检验统计量为23.2067，在[12.4, 39.36]这个区间内，即落在接受域，所以不拒绝原假设(fail to reject H0)，所以得到最后的结论：the population variance is not significantly different from 0.0144.
hemeng1788 · 2018年12月03日
弱弱的问下卡方计算是不是不在考试范围内？谢谢老师
菲菲_品职助教 · 2018年12月03日
在考试范围内哦！只是考得比较少。一般会考到一些定性的概念。计算基本不考。
hemeng1788 · 2018年12月04日
谢谢菲菲老师！
xinyuaaa · 2019年04月18日
老师 卡方分布表怎么看不是很理解，显著性水平为0.05，因为是双尾，左右各0.025，那直接查0.025加上正负号不就可以了吗？也就是【-39.36，39.26】之间不拒绝？
菲菲_品职助教 · 2019年04月19日
同学你好 查表方法我在这个评论里已经写的很详细啦 你可以再研究一下哦
NO.PZ2015120604000144 问题如下 Quintina concts a hypothesis to test whether the varianof the annually return is 0.0144. Then she selects ranm 25 year's ta a sample, Quintina figures out the varianof the sample is 0.013924. Assume the level of significanis 5%, whiof the following conclusion is least accurate? A.The population varianis not significant fferent from 0.0144. B.The population varianis significantly fferent from 0.0144. C.This hypothesis is appropriate to use the chi-square test. B is correct. The null hypothesis is H0: σ2=0.0144. It is appropriate to use the two-tailechi-square test.The test statistic is:=(25-1)*0.013924/0.0144=23.21The criticchi-square criticvalues are 12.4 an39.36.Because the test statistic falls between these two values,so Quintina fails to rejethe null hypothesis. So we conclu ththe population varianis not significantly fferent from 0.0144.题干是问whiis the least accurate?所以选 考试中会有需要记忆分布表的情况吗？
NO.PZ2015120604000144问题如下 Quintina concts a hypothesis to test whether the varianof the annually return is 0.0144. Then she selects ranm 25 year's ta a sample, Quintina figures out the varianof the sample is 0.013924. Assume the level of significanis 5%, whiof the following conclusion is least accurate? A.The population varianis not significant fferent from 0.0144.B.The population varianis significantly fferent from 0.0144.C.This hypothesis is appropriate to use the chi-square test. B is correct. The null hypothesis is H0: σ2=0.0144. It is appropriate to use the two-tailechi-square test.The test statistic is:=(25-1)*0.013924/0.0144=23.21The criticchi-square criticvalues are 12.4 an39.36.Because the test statistic falls between these two values,so Quintina fails to rejethe null hypothesis. So we conclu ththe population varianis not significantly fferent from 0.0144.题干是问whiis the least accurate?所以选rt 题干信息量略多，哪些关键词能看出来是卡方的考点
NO.PZ2015120604000144 问题如下 Quintina concts a hypothesis to test whether the varianof the annually return is 0.0144. Then she selects ranm 25 year's ta a sample, Quintina figures out the varianof the sample is 0.013924. Assume the level of significanis 5%, whiof the following conclusion is least accurate? A.The population varianis not significant fferent from 0.0144. B.The population varianis significantly fferent from 0.0144. C.This hypothesis is appropriate to use the chi-square test. B is correct. The null hypothesis is H0: σ2=0.0144. It is appropriate to use the two-tailechi-square test.The test statistic is:=(25-1)*0.013924/0.0144=23.21The criticchi-square criticvalues are 12.4 an39.36.Because the test statistic falls between these two values,so Quintina fails to rejethe null hypothesis. So we conclu ththe population varianis not significantly fferent from 0.0144.题干是问whiis the least accurate?所以选 如果在考试过程中也有类似的题，他会提供卡方的表吗？还是我们得自己记
NO.PZ2015120604000144 问题如下 Quintina concts a hypothesis to test whether the varianof the annually return is 0.0144. Then she selects ranm 25 year's ta a sample, Quintina figures out the varianof the sample is 0.013924. Assume the level of significanis 5%, whiof the following conclusion is least accurate? A.The population varianis not significant fferent from 0.0144. B.The population varianis significantly fferent from 0.0144. C.This hypothesis is appropriate to use the chi-square test. B is correct. The null hypothesis is H0: σ2=0.0144. It is appropriate to use the two-tailechi-square test.The test statistic is:=(25-1)*0.013924/0.0144=23.21The criticchi-square criticvalues are 12.4 an39.36.Because the test statistic falls between these two values,so Quintina fails to rejethe null hypothesis. So we conclu ththe population varianis not significantly fferent from 0.0144.题干是问whiis the least accurate?所以选 criticvalue 根据公式不应该是 24*23.21 吗？。criticvalue 地两个值如何算出来的？
NO.PZ2015120604000144问题如下 Quintina concts a hypothesis to test whether the varianof the annually return is 0.0144. Then she selects ranm 25 year's ta a sample, Quintina figures out the varianof the sample is 0.013924. Assume the level of significanis 5%, whiof the following conclusion is least accurate? A.The population varianis not significant fferent from 0.0144.B.The population varianis significantly fferent from 0.0144.C.This hypothesis is appropriate to use the chi-square test. B is correct. The null hypothesis is H0: σ2=0.0144. It is appropriate to use the two-tailechi-square test.The test statistic is:=(25-1)*0.013924/0.0144=23.21The criticchi-square criticvalues are 12.4 an39.36.Because the test statistic falls between these two values,so Quintina fails to rejethe null hypothesis. So we conclu ththe population varianis not significantly fferent from 0.0144.题干是问whiis the least accurate?所以选老师。。答案全出来了。。。用哪个值跟12.401和39比啊