Large Sample z Test

If a large number of results are available so that s is a good estimate of s, the z test is appropriate. The procedure that is used is summarized below:

The rejection regions are illustrated in Figure 7-2 for the 95% confidence level.

Note that for H_a: μ ≠ μ⁰, we can reject for either a positive value of z or for a negative value of z that exceeds the critical value. This is called a two-tailed test since rejection can occur for results in either tail of the distribution. For the 95% confidence level, the probability that z exceeds z_crit is 0.025 in each tail or 0.05 total. Hence, there is only a 5% probability that random error will lead to a value of z ≥ -z_crit or z ≤ -z_crit. The significance level overall is α = 0.05. From Table 7-1, the critical value of z is 1.96 for this case. If instead our alternative hypothesis is Ha: μ > μ⁰, the test is said to be a onetailed test. In this case, we can reject only when z ≥ z_crit. Now, for the 95% confidence level, we want the probability that z exceeds z_crit to be 5% or the total

Figure 7-2 Rejection regions for the 95% confidence level. (a) Two-tailed test for H_a: μ ≠ μ⁰. Note the critical value of z is 1.96 . (b) One-tailed test for H_a: m > m⁰. The critical value of z is 1.64 so that 95% of the area is to the left of zcrit and 5% of the area is to the right. (c) One-tailed test for H_a: μ < μ⁰. The critical value is again 1.64 so that 5% of the area lies to the left of -z_crit.

مواضيع ذات صلة

الشكل الوضعي للسكريات الأحادية configuration of monosaccharides

نظام استخلاص الجزئيات البسيطة

اختيار الطور الجديد وعدد مرات الاستخلاص

ميكانيكية الاستخلاص

طبيعة الصنف المستخلص

الاستخلاص بالمذيب

امتصاص الشعاع الكهرومغناطيسي وطيف الامتصاص

الطرق الكيميائية الطيفية في التحليل.

طبيعة الكيمياء التحليلية

التحليل بالحقن الجرياني المتقطع Batch flow injection analysis

الحقن الجرياني متعدد التخفيف Multi-commutation in FIA

التحليل بالحقن المتعاقب Sequential Injection Analysis