Issues with Horoscopes and Some Personality tests

Which horoscope are you?  Would you read the predictions for your horoscope for the upcoming week, month, or year?
Do you believe it?
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When I was in my teens, I used to love reading my weekly and annual horoscopes to find out my upcoming fortunes or mishaps in the near future.  Some similar phrases include those in the below paragraph: 
You have a great need for other people to like and admire you.  You have a tendency to be critical of yourself.  You have a great deal of unused capacity which you have not turned to your advantage.  While you have some personality weaknesses, you are generally able to compensate for them.  Disciplined and self-controlled outside, you tend to be worrisome and insecure inside.  At times you have serious doubts as to whether you have made the right decision or done the right thing.  You prefer a certain amount of change and variety and become dissatisfied when hemmed in by restrictions and limitations.  You pride yourself as an independent thinker and do not accept others' statements without satisfactory proof.  You have found it unwise to be too frank in revealing yourself to others.  At times you are extroverted, affable, sociable, while at other times you are introverted, wary, reserved.  Some of your aspirations tend to be pretty unrealistic.  Security is one of your major goals in life.
If you find most of the paragraph congruent with your life, you may be vulnerable to the Barnum / Forer effect.  According to Wikipedia, this effect is "common psychological phenomenon whereby individuals will give high accuracy ratings to descriptions of their personality that supposedly are tailored specifically to them but that are, in fact, vague and general enough to apply to a wide range of people."  The above paragraph is also based from the same link as the definition.

These statements about your fortune or personalities tend to be very generalised, but yet at the same time very convincing.  Along with the cognitive bias of confirmation bias (tendency to search for, interpret, focus on and remember information in a way that confirms one's preconceptions), there is a high chance that the information will be perceived in a personalised manner by the reader.
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To reduce these effects of these cognitive biases, you have to ask yourselves these questions:
  • How was the measurements done?  Are the source of the test or measurement a reliable one?
  • Are the measurements valid (measuring what they are supposed to measure) and/or have been tested to be valid?
  • Are the measurements reliable (producing consistent results over a period of time) and/or have been tested to be reliable?
  • Are the results reliable? Can we trust the results?
  • Are the results specific enough, such that they can be perceived/read in an accurate manner? 

My training in psychology, and especially in research, has cultivated me to critically question things and check out the "facts" if they are accurate and valid.  This has sometimes resulted in me questioning my own perceptions and reflecting on my own knowledge.  However, in the purpose of seeking knowledge, it is a must to be done.  Unfortunately our society are still very susceptible to these very common cognitive biases, resulting in these unreliable yet very marketable (easy to understand and sell to the general public) tests to flourish in the market.

To conclude, I no longer read my horoscopes, but sometimes have to do these assessments in my organisation.  As I do them, I will research on their validity and reliability so as to have a better understanding of whether they will be useful to me.  If they are not, I will take the results with a "huge pinch of salt".
The next post this month will cover what students should note to be a valid and reliable measurement/test, and the different types of validity and reliability measurements.