In English, gerunds can stand by themselves in phrases:
I have seen standalone gerunds used as newspaper article titles. In Spanish, the use of gerunds is a lot stricter. So are phrases such as "Generalizando desde muestras" and "Generalizando desde experimentos" wrong?
As @neizan said and as I explained in this other answer, gerunds cannot be used as nouns, so many times English gerunds are translated by infinitives in Spanish, mainly when the gerunds are the subject of the sentences, as in @neizan's example...
Anyway we would need more context, but I wouldn't say your sentences are wrong. You can find many examples of phrases with standalone gerunds in Spanish, the only requirement is that they cannot acts as the subject of the phrase (although in this case I'm not sure whether you can call it standalone)...
Examples:
Pensándolo bien, prefiero no hacerlo.
Repitiendo el ejercicio muchas veces, conseguirás entenderlo.
Agitando el recipiente se consigue mezclar bien el contenido.
Generalizando los resultados obtenidos se pueden sacar conclusiones equivocadas.
All these sentences are correct because the gerund form is not the subject...
EDIT: If you mean sentences like "Generalizando desde muestras" as the title of an article, I'd say it's not common and most of the times you should probably use a noun ("La generalización").
Yet again, I wouldn't say it's wrong to use a gerund in sentences like that. For example, I can publish a photo of my birthday party and post as a comment "¡Celebrando mi cumpleaños!".
EDIT 2: I've just found 3 examples of articles written by Arturo Pérez Reverte (a famous Spanish writer), published in his section within the national newspaper El País whose titles are:
Recordando Krasny Bor
Disfrazando a las criaturas
Okupando a Góngora
And these are just examples I've found in 1 min...
I'm not a native Spanish speaker, but those two phrases sound wrong to me. A full sentence would provide more insight as to context. However, if you mean something, "generalizing from experiments, we can say that most boys in Spain prefer soccer over baseball," then I would formulate it like this: "la generalización extraida/deducida del experimento es que..." or "a partir de los resultados del experimento, se puede decir que..." However, I might be making a wrong assumption about what you mean.
As to your question in general, these examples are using the gerund as a noun. Generally, in Spanish I've seen gerunds replaced by infinitive forms of verbs to express the same. Take the following example:
En: Eating sweets before supper is not good.
Sp: Comer chuches antes de cenar no es bueno.
