May I ask further about the Null hypothesis in Week 7, Doing Research 1?

Applying the cognitive bottom-up process and using inductive reasoning often shapes my perspective to see life as beautiful and human nature as good. Based on this, I propose the hypothesis that "Life has inherent beauty."

However, when transitioning to deductive reasoning, I can fall prey to confirmation bias. I tend to find more positive aspects, thus further reinforcing the aforementioned viewpoint. By evaluating my personal experience, I understand the meaning of scientific falsification. 

When I apply the hypothetico-deductive approach, is it correct if I present a counter-argument as "Life and human nature are inherently bad"? In this case, the Type 1 error would be: Reality is bad, but observation shows it as good. The Type 2 error would be: Reality is good, but observation shows it as bad. Is it right?

However, if we apply that scientific perspective to everyday life, two situations can arise:

I am still unsure if the Null hypothesis should be "Bad" or not. I believe it should be "Neutral", but there would be three variables: Neutral, Good, and Bad, resulting in 9 possible scenarios instead of 4. I would appreciate your clarification on this matter.

This is indeed a long premise, arguments and end with the straightforward question about Null hypothesis. Rather than go to details, let me just answer your query with a simple answer:

i. Do not take 'neutral' because it will complicate things as you already aware.
ii. It is acceptable to take the Null as you first hypothesize it, that is "Life is beautiful". This is an acceptable (common hypothesize).
iii. so your Ho is: Life is Beautiful
iv. your alternative hypothesis (Ha) will be:  Life is not beautiful.
v. You can only reject the Null if and only if you have 'confidence' that your error will be less than 5% (due to chance). If and when this is proven, your conclusion is to state: I have rejected the Null.  (Note: never state I accept Null because this is scientifically not correct).
vi. likewise, if you discover the error is >5%, then your conclusion will be "I fail to reject Null" (for that moment of time, until or when the time comes, you have evidence that leads you to be able to reject Null).
vii. this is how scientific reasoning regarding hypothesis is discussed, argued and explained.

so in this case, you be committing type 1 error IF  it is TRUE(for a fact) that "life is beautiful" yet you mistakenly REJECT Ho.

And, you be committing type 2 error IF it is NOT TRUE (indeed false) that "life is beautiful" because you DID NOT REJECT Ho.


Question 2: Internal and External validity

Hi, my question is: is it possible for a result to have both validity high at the same time? Or it can only indicate one validity high?
Also, since the double-blind RCT receives many credits, can researchers use that method for all research to strengthen their studies?

i.Not sure what you mean by 'both' validity.
ii. not necessarily. depends on the context and complexity of the said research study.

 

•        In case the p-value is equal or more than .05, the null hypothesis is accepted, is that right?
From my understanding, if p value > 5%, we cannot conclude anything about the relationship. Is it right?

My response:

i. The proper way to discuss/mention/write/say about "null hypothesis" is this:
    "null hypothesis FAIL TO BE REJECTED"  this is the correct way of stating this situation or result.
  DO NOT say " null hypothesis is accepted". 
Reason = At that moment of time, at that circumstances of obtaining said result, we DO NOT HAVE OTHER evidences or proofs- that may LEAD us to reject. Thus it is more ACCURATE to say: 
   " at this point of time (getting said results), we can only confidently say:  FAIL TO REJECT.  (versus ACCEPT).

By saying ACCEPT, you are determining to a certain degree of confidence "DECLARING NO DIFFERENCE" which in itself is a danger!

But by saying "at this point of time (getting said results), we can only confidently say : FAIL TO REJECT NULL, until the time comes, in the future, where we can obtain other evidences or proof that we can FINALLY REJECT NULL!.

ii. IF p > than 0.05, the conclusion is again "FAIL TO REJECT NULL"  (not accept Null)>