Significant correlation, not significant coefficient

In summary, the conversation discussed two questions. The first was about running a panel data regression test and comparing the correlations between the independent variables and the dependent variable. The results showed a significant correlation between "Anleggsmidler/eiendeler" and the dependent variable, but when the regression analysis was done, the significance disappeared. The second question was about including standardised coefficients to fixed effects regression results in Stata, which the beta command did not work for. The expert suggested that the multicollinearity in the data may be causing unreliable estimates and recommended trying a reduced model without "Anleggsmidler/eiendeler" to see if that improves the results.
  • #1
monsmatglad
76
0
A couple of questions today. First. I am running a panel data regression test. First I check the correlations between the independent variables and the dependent variable. these are the results.
upload_2017-4-30_17-32-50.png


The D/(D+Em) is the dependent variable, and the independent are the 4 variables most adjacent. Disregard the two outer variables (the red area). The independent variable "Anleggsmidler/eiendeler" has a correlation coefficient (pearson's) to the dependent variable of ,177 and this is a very significant result as you can see. However, when I do the regression analysis (as shown below), the relation between "Anleggsmidler/eiendeler" and the dependent variable is not significant at all. How come the results are so different in terms of significance?

upload_2017-4-30_17-38-18.png

Second question is is there any command to include standardised coefficients to fixed effects regression results in stata? the beta command does not work when I use fixed effects regression (i am pretty green when it comes to Stata). Any advice on these two questions? Thanks in advance!
 
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  • #2
You have pretty substantial multicolinearity in this data. The estimates of individual coefficients will be unreliable in the regression.
 
  • #3
hey. I used a VIF-test and it produced the following numbers: I understand that it differs what is regarded as acceptable, but as far as I know, below 10 is usually no disaster (based on google searches, not on my acumen).

Variable VIF 1/VIF
lndriftsin~r 5.72 0.174921
anleggsmid~r 5.02 0.199399
totalrenta~t 1.34 0.743779
markedbok 1.18 0.845347
Mean VIF 3.31
 
  • #4
By the time the (estimated) effects of the other variables are taken into account, there is not enough left for Anleggsmidler/eiendeler to be statistically significant. It should be removed from the model and the linear regression should be re-run without it.
 
  • #5
monsmatglad said:
I used a VIF-test
Instead, just try running a reduced model deleting totalrentabilitat
 

1. What does it mean when there is a significant correlation but not a significant coefficient?

When there is a significant correlation but not a significant coefficient, it means that there is a relationship between two variables, but the strength of that relationship is not strong enough to be considered statistically significant. In other words, there may be a small or weak effect between the two variables that is not strong enough to be considered meaningful or reliable.

2. How is a significant correlation different from a significant coefficient?

A significant correlation indicates that there is a relationship between two variables, while a significant coefficient indicates the strength and direction of that relationship. In other words, a significant correlation means that the two variables are related in some way, while a significant coefficient tells us how strong that relationship is.

3. Can a significant correlation exist without a significant coefficient?

Yes, it is possible for a significant correlation to exist without a significant coefficient. This means that there is a relationship between two variables, but the strength of that relationship is not strong enough to be considered statistically significant. This could be due to a small sample size or other factors that may affect the strength of the relationship.

4. What factors can affect the significance of a correlation or coefficient?

Several factors can affect the significance of a correlation or coefficient, including sample size, measurement error, and the type of data being analyzed. Additionally, the strength of the relationship between the two variables and the variability of the data can also impact the significance level.

5. How should a significant correlation without a significant coefficient be interpreted?

A significant correlation without a significant coefficient should be interpreted with caution, as it indicates a weak or small relationship between two variables. It is important to consider other factors and conduct further analysis to determine the strength and reliability of the relationship before drawing any conclusions.

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