[Carlo Lazzaro]

Nicola:
1) just check if the resulting turning point lies within the ranhe of yuor variable looking at -summarize- results;
2) it mean that you have to study the behaviour of the 1st derivative to confirm that what yoi've obtained is a max or a min.

[Nicola Rossi]

Dear Carlo,
thank you very much for your prompt reply.

1. Turning point between min and max of the variable. Correct?
2. Can I interpret it from the output below?

Specification: f(x)=x^2
Extreme point:  17.28066

Test:
H1: Inverse U shape
vs. H0: Monotone or U shape 


Lower bound      Upper bound

Interval                    0               50
Slope                .0407253        -.0771096
t-value              2.597816        -3.066287
P>t                .0047663         .0011155


Overall test of presence of a Inverse U shape:
t-value =      2.60
P>t   =    .00477

95% Fieller interval for extreme point: [8.6767915;    24.567584]

Thank you again for your support.
Best,
N

[Carlo Lazzaro]

Nicola:
yes, your turning point is a minimum.

[Nicola Rossi]

Thank you, Carlo.
Kind Regards,
Nicola