Do you have a link to the study?
The procedure is not complex.
Take for example what we knew 100 years ago by logic.
Every single life form we knew ultimately derived its energy from the sun (either directly like plants or by consuming plants or by consuming consumers etc).
By inductive reasoning, we can then say every lifeform we have not discovered ALSO derives its energy ultimately from the sun (or lets say stellar source).
And this continues and basically establishes a high probability of the absolute truth till something breaks the logic chain like it did in this very case.
In the latter part of the 20th century with deep sea diving becoming more advanced, lifeforms were found in underwater trenches that conclusively do not need the sun to survive and form a completely segregated ecosystem based on geothermal energy from volcanic vents. Other such lifeforms were found in deep dark caves as well.
So inductive logic is not infallible because it ultimately works on probabilities.
Therefore for your study, the reason why it can't really be called pure inductive reasoning is that the sample size was not large enough. 1000 people cannot represent humanity and all it would take is one person that has the same astrological conditions but not the consequences observed in the study group. Then when we establish its only percentages (i.e something more likely given something astrological), you need to have an excellent sample group and statistical analysis to back it up inductively.
Deductive reasoning is even much more closed and sound....because it doesn't care about the validity of the initial axiom (i.e if the premise is absolutely true) say something like all life dies but only about the logical process (since i am a lifeform, i will die). Thus deductive reasoning is not based on probabilities (other than possibly the original premise that it doesnt care about). It can be used in an unsound way however like say saying everyone who is born in england speaks english > I speak english > therefore I am english (valid but unsound!!!!)
This picture may help:
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