Question

The body mass index (variable BMI) provides an indication of a person’s level of body fat as follows: healthy weight, 20–25; overweight, >25–30; obese, greater than 30. Excess body weight is, of course, related to diet, but, in turn, what we eat de- pends on who we are in terms of culture and our en- tire life experience. Based on an analysis using mean weight, can you conclude that white people have a healthy weight? Can you conclude that based on mean weight, white people are overweight? You will do the analysis based first on the data from the first interview, create a subset from the data file using daycode = 1, and a second time using data from the second interview, create a subset from the data file using daycode = 2. Note that there are differences in the responses between the first and second interviews.

Please help me by explain this step by step!

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Answer 1

In the above box diagram, it shows the process for analysis and accepting or rejecting the Null Hypothesis.

Let's start explaining this in step by step.

• Firstly we have to setup the Hypothesis were,  $H_o$  is null hypothesis and $H_1$   is alternative hypothesis. Here, we 3 different hypothesis are set .
• Next, we will will choose the level of significance ($\alpha$), through which we will decide the rejection area and acceptance area in the curve.
• Next, if we know the value of Variance then we can use Standardizing normal Z distribution. Otherwise ,we will use students t- distribution because from there we can use the sample variance ($s^2$) ,we can be obtained from the samples.
• Now, on concerning with Z-scores we will have to calculate critical value, which is nothing but the boundary of the acceptance region and rejection region. On concerning to students t- distribution we can also calculate the critical value .

ru-liit Žo/2 σ i lor upper cntical value

Tu L = μ,-Zo/201 for lower critical ualue

the upper formula is same for both the case i.e. for Z-scores and t- distribution.

• Now, we will get three critical values in both the cases because we have setup 3 different hypothesis.
• Now, further calculation of critical value we can decided whether to reject or accept the null hypothesis.
• As in concerning to Z scores method , in 1st hypothesis if our mean becomes greater than upper critical value or vice-versa then we will reject the null hypothesis. In 2nd hypothesis ,if mean value is greater than the critical value then we will reject our null hypothesis. In 3rd hypothesis, if mean value is less than calculated critical value then we will reject the null hypothesis.
• Similarly, in case of Students t- distribution, we will reject or accept the null hypothesis .

It should be noted that in hypothesis 2 and hypothesis 3 , we are finding upper critical value and lower critical value respectively.