Soru

Zorluk: KolayInferential Statistical Tests

A clinical study is conducted to evaluate the effect of a novel SGLT2 inhibitor on fasting blood glucose levels in patients with type 2 diabetes. The investigators recruit a total of 120 patients and randomly assign them in a 1:1 ratio to either the intervention group (n=60n = 60) or the placebo group (n=60n = 60). The primary outcome is the absolute change in fasting blood glucose (measured in mg/dL) from baseline to week 12. The data for this outcome are continuous and demonstrate a normal distribution in both groups. The researchers analyze the primary outcome by comparing the mean change between the two distinct groups using an unpaired Student t-test. What is the degrees of freedom associated with the statistical test for this primary analysis?

Cevap: 118

Cevap

118
The unpaired Student t-test is utilized to compare the means of two distinct, independent groups when the dependent variable is continuous and normally distributed. The degrees of freedom (dfdf) for this test reflects the number of independent values that can vary in the analysis. Because the mean is estimated separately for each of the two groups, two degrees of freedom are lost from the total sample size (NN). Therefore, the formula is df=n1+n2−2df = n_1 + n_2 - 2. Given that each group has 60 patients, the calculation is 60+60−2=11860 + 60 - 2 = 118.

Adım Adım Çözüm

1
Identify the statistical test being used and the relevant parameters from the study design.
The test is an unpaired Student t-test. The sample sizes are n1=60n_1 = 60 and n2=60n_2 = 60.
Determining the correct test is required to know which degrees of freedom formula to apply.
2
Apply the degrees of freedom formula for the identified statistical test.
The formula is df=n1+n2−2df = n_1 + n_2 - 2.
In an unpaired t-test, one degree of freedom is lost for each group's mean that is estimated from the sample data.
3
Calculate the final numerical value.
df=60+60−2=118df = 60 + 60 - 2 = 118.
Substituting the given group sizes yields the exact degrees of freedom.

Anahtar Kavram

Degrees of freedom for an unpaired Student t-test
Bu soruyu puanla