Hypothesis Testing

来源：百度知道 编辑：UC知道 时间：2024/06/14 08:55:03
In a study of iron deficiency among infants, the blood hemoglobin levels were compared between two samples of infants, who follow different feeding regimes. One group consisted of breast fed infants, while the other group was fed with a standard baby formula without any iron supplements. The summary of results on blood hemoglobin levels for infants at 12 months of age is as follows:

Group Sample size Mean Standard deviation
Breast –fed 23 13.3 1.7
Baby formula 19 12.4 1.8

Is there sufficient evidence to indicate that the mean blood hemoglobin level is higher among the breast-fed babies? Test at  = 0.05.
[sp2 = 3.0475; t = 1.663; Do not reject H0]

Hypothesis: A statement about the value of a population parameter developed for the purpose of testing.
Hypothesis testing:假设检验 Based on sample evidence and probability theory; Used to determine whether the hypothesis is a reasonable statement and should not be rejected, or is unreasonable and should be rejected.

Step One: State the null and alternate hypotheses
Null Hypothesis H0 零假设或空假设:A statement about the value of a population parameter
Alternative Hypothesis H1备择假设: A statement that is accepted if the sample data provide evidence that the null hypothesis is false
Three possibilities regarding means(The null hypothesis always contains equality.)
H0:μ=0 H0:μ≤0 H0:μ≥0
H1:μ≠0 H1:μ>0 H1:μ<0
Step Two: Select a Level of Significance. 显著性水平
Level of Significance: The probability of rejecting the null hypothesis when it is actually true; the level of risk in so doing.
Type I Error: Rejecting the null hypothesis whe