Since IQ scores approximate a normal distribution we can estimate the percentage of scores in a given range using what's known as the empirical rule. The empirical rule is that in a normal curve 68% of scores will fall within one standard deviation of the mean, 95% within 2 standard deviations, and 99.7% within 3 standard deviations. IQ has a estimated mean of 100 and a standard deviation of about 15. This means 50% of people will score below 100 and about 34% will fall between 100 and 115, leaving approximately 16% of scores above 115. So at a score of 115 a person has scored higher than about 84% of the general population (higher than the 50% below 100 and the 34% between 100-115) and lower than about 16% of the population. Note that the image is simplified and doesn't extend to the full range of possible scores (and IQ scores are less reliable at the extremes), so it doesn't show 100% of scores, but we can expect about 13.5% from 115-130, then somewhere around 2% from 130-145, and 0.1% from 130-145, giving a total of 15.6%, which can be rounded to about 16% (as there are also still some scores above 145). Hope this helps!
These are practice questions that I've written, based on concepts in most introductory psychology textbooks, and covered in the student guide I've written, Master Introductory Psychology. Free Pdf files of these questions and explanations will also be available on my website www.psychexamreview.com soon.
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Thank you, these videos have helped me to better understand the readings I have already done on intelligence, 10/10
Glad to hear that!
Did 9 out of 10
Well done!
Can you explain question 9??
Since IQ scores approximate a normal distribution we can estimate the percentage of scores in a given range using what's known as the empirical rule. The empirical rule is that in a normal curve 68% of scores will fall within one standard deviation of the mean, 95% within 2 standard deviations, and 99.7% within 3 standard deviations. IQ has a estimated mean of 100 and a standard deviation of about 15. This means 50% of people will score below 100 and about 34% will fall between 100 and 115, leaving approximately 16% of scores above 115.
So at a score of 115 a person has scored higher than about 84% of the general population (higher than the 50% below 100 and the 34% between 100-115) and lower than about 16% of the population.
Note that the image is simplified and doesn't extend to the full range of possible scores (and IQ scores are less reliable at the extremes), so it doesn't show 100% of scores, but we can expect about 13.5% from 115-130, then somewhere around 2% from 130-145, and 0.1% from 130-145, giving a total of 15.6%, which can be rounded to about 16% (as there are also still some scores above 145). Hope this helps!
@@PsychExamReview thank you so much! these have been wonderful to prepare for the EPPP!
@@Dr.BrittanyLeibowitz No problem, glad to hear that!
Give us a sources please
These are practice questions that I've written, based on concepts in most introductory psychology textbooks, and covered in the student guide I've written, Master Introductory Psychology. Free Pdf files of these questions and explanations will also be available on my website www.psychexamreview.com soon.
@@PsychExamReview can you please explain PASS theory of intelligence