Correlation Test 4D00B9
1. **Problem Statement:**
We are given correlation coefficients between first weekend gross, regional gross, and worldwide gross of six movies. We need to test if there is a significant linear relationship between these variables at the 0.05 significance level.
2. **Hypotheses:**
The correct hypotheses for testing correlation significance are:
$$H_0: \rho = 0$$
$$H_1: \rho \neq 0$$
This means the null hypothesis states no linear correlation, and the alternative states there is a correlation.
3. **Critical Values:**
For a two-tailed test with $\alpha = 0.05$ and degrees of freedom $df = n-2 = 6-2=4$, the critical t-values are:
$$\pm t_{\alpha/2, df} = \pm 2.7764$$
4. **Test Statistic Formula:**
The test statistic for correlation $r$ is:
$$t = \frac{r \sqrt{n-2}}{\sqrt{1-r^2}}$$
where $n=6$.
5. **Given Correlations and Calculations:**
- First weekend gross and regional gross: $r = -0.1409$
$$t = \frac{-0.1409 \times \sqrt{4}}{\sqrt{1 - (-0.1409)^2}} = \frac{-0.1409 \times 2}{\sqrt{1 - 0.0199}} = \frac{-0.2818}{0.9900} = -0.2846$$
- First weekend gross and worldwide gross: $r = -0.3116$
$$t = \frac{-0.3116 \times 2}{\sqrt{1 - 0.3116^2}} = \frac{-0.6232}{\sqrt{1 - 0.0971}} = \frac{-0.6232}{0.9515} = -0.6558$$
- Regional gross and worldwide gross: $r = 0.9491$
$$t = \frac{0.9491 \times 2}{\sqrt{1 - 0.9491^2}} = \frac{1.8982}{\sqrt{1 - 0.9008}} = \frac{1.8982}{0.3123} = 6.0775$$
6. **Decisions:**
- For first weekend vs regional gross: $|t|=0.2846 < 2.7764$, do not reject $H_0$. Insufficient evidence of linear relationship.
- For first weekend vs worldwide gross: $|t|=0.6558 < 2.7764$, do not reject $H_0$. Insufficient evidence of linear relationship.
- For regional vs worldwide gross: $|t|=6.0775 > 2.7764$, reject $H_0$. Significant linear relationship exists.
**Final answers:**
- Hypotheses: $H_0: \rho=0$, $H_1: \rho \neq 0$
- Critical values: $-2.7764, 2.7764$
- Test statistics: $t_{STAT} = -0.2846$, $-0.6558$, $6.0775$
- Decisions: No significant linear relationship for first weekend vs regional and worldwide gross; significant relationship for regional vs worldwide gross.