Table of Contents

## What is the score that divides the distribution into two such that 75\% of the cases is below it?

Quartile Deviation

The Quartile Deviation in “research talk” the quartile deviation is one half of the difference between the upper quar- tile and the lower quartile in a distribution. In English, the upper quartile is the 75th per- centile, that point below which are 75\% of the scores.

**What is the corresponding z-score of the average score?**

The value of the z-score tells you how many standard deviations you are away from the mean. If a z-score is equal to 0, it is on the mean. A positive z-score indicates the raw score is higher than the mean average. For example, if a z-score is equal to +1, it is 1 standard deviation above the mean.

### How do you find the z-score when given the actual value?

The z score is the numerical value which represents how many standard deviations a score is above the mean. So, for example, if we have a z score of 1.5, a mean of 80, and a standard deviation of 10, this means that the raw score that was obtained is, raw score= µ + Zσ = (80) + (1.5)(10)= 95.

**What is the score that divides the distribution?**

median

The median is the point on the scale that divides the distribution into halves, with 80 scores above and 80 scores below.

#### Which of the following is the score that represents the exact middle in a distribution?

the median, symbolized Mdn, is the middle score. It cuts the distribution in half, so that there are the same number of scores above the median as there are below the median. Because it is the middle score, the median is the 50th percentile.

**What is Z score used for?**

The standard score (more commonly referred to as a z-score) is a very useful statistic because it (a) allows us to calculate the probability of a score occurring within our normal distribution and (b) enables us to compare two scores that are from different normal distributions.

## How do you find the z-score of a proportion?

You can transform P̄ into a z-score with the following formula: Z Score for sample proportion: z = (p̄ – p) / SE.

**How do you find the Z score in statistics?**

z = (x – μ) / σ For example, let’s say you have a test score of 190. The test has a mean (μ) of 150 and a standard deviation (σ) of 25. Assuming a normal distribution, your z score would be: z = (x – μ) / σ