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z scores
IQ scores in the population have a mean of 100 and a standard deviation of 15. If Bob has an IQ of 83, what percent of people have scores lower than him? If Sally has an IQ of 97, what percent of people have scores higher than her? What percent of people have IQs between 80 and 120?
If a random variable X has a normal distribution with mean m and standard error s, then the z-score corresponding to the value X = x is (x - m)/s.
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When to you use a z scores or t scores?
If the distribution is Gaussian (or Normal) use z-scores. If it is Student's t, then use t-scores.
Are normal scores the same as z-scores?
They should be.
What is one advantage of transforming X values into z-scores?
True or False, One major advantage of transforming X values into z-scores is that the z-scores always form a normal distribution
Is the Z-test the same as Z-scores?
No, the Z-test is not the same as a Z-score. The Z-test is where you take the Z-score and compare it to a critical value to determine if the null hypothesis will be rejected or fail to be rejected.
Are all standard scores z-scores in statistics?
Yes, although the z-scores associated with p-values of 0.01 and 0.05 have special significance, perhaps mostly for historical reasons, all possible z-scores from negative infinity to positive infinity have meaning in statistical theory and practice.
In a standard normal distribution about percent of the scores fall above a z score of 300?
A Z score of 300 is an extremely large number as the z scores very rarely fall above 4 or below -4. About 0 percent of the scores fall above a z score of 300.
What is the formula for z scores?
Z = (x minus mu) divided by sigma.
How do you find normal distribution of z-scores?
z-scores are distributed according to the standard normal distribution. That is, with the parameters: mean 0 and variance 1.
What z-score separates the top 10 percent from the rest of the scores?
z = 1.281551
Do z-scores have a units of measure?
No, they do not. They are pure numbers.
How can you use a z score to determine outliers?
Best to use a histogram i think! z scores can probably be used too however they seem more a method of how to transform outliers in workable scores.
Stacey's average score on three maths tests is 84 Her last two test scores were 79 and 93 What was her first test score?
Average of three test scores is 84 can be written (x+y+z)/3=84. If you know two of the scores then (79+93+z)/3=84, so to solve for z, 79+93+z=84*3 z=252-79-93 z=80 The first test score was 80
