ANOVAs from SPSS and R report different degrees of freedom. Which are correct? I am conducting a reanalysis of some data. The dv is continuous (beta value ie neural activity) and the iv is categorical (position) with three levels (1, 2, 3). There are 126 observations. The original analysis was conducted in SPSS and the original paper reports F(2,82) = 43.058, p = 0.00.  I am conducting my analysis in R, and I am getting residuals df of 123. Here is the table:
> summary(aov(Beta ~ Position, data = cFFA_same))
                  Df Sum Sq Mean Sq F value Pr(>F)  
factor(Position)   2  118.3   59.13    4.08 0.0193 *
Residuals        123 1782.7   14.49                 
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1


I am quite poor in statistics - can anyone explain which df are correct and why/how they affect the F statistic and p value in this way?
Edit: The design is repeated measures, and I have seen that I should be using aov_car from the afex package instead of Anova/aov. However, I get the same output for both:
Anova(lm(Beta ~ Position, data = cFFA_half))

Anova Table (Type II tests)

Response: Beta
           Sum Sq  Df F value Pr(>F)
Position    50.73   2  1.4999 0.2272
Residuals 2080.08 123    


aov_car(Beta ~ Position + Error(Beta), data = cFFA_half)

Contrasts set to contr.sum for the following variables: Position
Anova Table (Type 3 tests)

Response: Beta
    Effect     df   MSE    F  ges p.value
1 Position 2, 123 16.91 1.50 .024    .227
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘+’ 0.1 ‘ ’ 1

I was also not sure what to use as the error term. Is this the problem?

You have different degrees of freedom for the residuals 123 vs 82.
This indicates that you probably are

*

*working with different data (the original paper does not have 126 observations)

or

*

*you are doing several steps differently (e.g. the original paper might have used some selection of the data or has additional variables in the model).

It is not possible to see what it is exactly. In order to answer more specifically about this you should make your question more detailed. Ideally the question should be made reproducible (e.g. provide links to the data and original research).
