Chapter 4: Z Scores

How do you use a unit normal table to find the area of the shaded portion of the curve?

1) If the shaded area is MORE than 50% of the distribution, use the BODY column in the table 2) If the shaded area is LESS than 50% of the distribution, use the TAIL column in the table

What is the formula to show the exact relationship between the population standard deviation (δ) and the standard deviation of the distribution of sample means?

SEMp = δ/ √N

True or False: the sum of the positive deviation scores will ALWAYS equal the sum of the negative deviation scores

True

Unit Normal Table

a mathematical table for the values of the cumulative distribution function of the normal distribution

Central Limit Theorem

a statistical theory that states that given a sufficiently large sample size from a population with a finite level of variance, the mean of all samples from the same population will be approximately equal to the mean of the population

When finding the area of the distribution that is above or below a negative z score, you... a. need a different z table with negative values in it b. simply look up the absolute value of the z score and then determine if you need to use the tail or body column of the table

b. simply look up the absolute value of the z score and then determine if you need to use the tail or body column of the table

What does the value of a Z Score indicate?

how typical a particular score is within bunch of scores, also we can use Z Scores to compare and standardize scores from different groups of data

Distribution of Sample Means

is all the possible random sample means of a given sample size (N) from a particular population

Z Scores

tells if a score is above or below a population mean, and informs whether a score's deviation from the mean is relatively large or relatively small compared with the deviations of the rest of the data

What does the sign of a Z Score indicate?

the numerical value of the z-score corresponds to the number of standard deviations between X and the mean of the distribution

What formula is used to calculate/ locate the Z Score?

z = X - μ/ δ