Normal Curve Flashcards

Questions and Answers

What is a normal distribution?

A unimodal, symmetrical, bell-shaped curve (correct)

A distribution where scores are evenly spread

A distribution with two modes

None of the above

Most psychological variables are approximately normally distributed.

True

What is the mathematical formula for normal distribution?

You don't need to know it.

The mean, median, and mode are all located at the ______ percentile in a normal distribution.

50th Signup and view all the answers

Which of the following is NOT a characteristic of normal distribution?

It can have a negative standard deviation Signup and view all the answers

What is the area under a standardized normal curve?

1 or 100% Signup and view all the answers

What does it mean when tails approach the x-axis but never touch it?

This indicates that the probability of extreme values decreases but never reaches zero. Signup and view all the answers

How can a z score be translated into a population percentage?

By marking z scores on the normal distribution. Signup and view all the answers

What information can be derived from a Normal Curve Table?

Exact percentage of scores between any two points. Signup and view all the answers

To find the percentile corresponding to a z score, you first convert the raw score to a Z score and then ______.

shade in the area for which you are finding the percentage. Signup and view all the answers

What is the process to determine Z scores from a percentile?

Draw a normal curve, shade the area, and find the exact Z score. Signup and view all the answers

Study Notes

Normal Distribution Overview

Normal distribution is a bell-shaped, symmetrical curve with most scores clustering around the mean.
Mean, median, and mode are identical in a normal distribution, emphasizing its symmetry.
This distribution is widely applicable and assumed for many psychological and statistical variables.

Characteristics of Normal Distribution

Mathematically defined and theoretical; real data may approximate this but not be perfectly normal.
Mean, median, and mode reside at the 50th percentile.
Both tail ends of the curve approach the x-axis but never actually intersect it.
The total area under a standardized normal curve equals 1 (or 100%).
Standard deviation (SD) can represent any positive value, affecting the width of the curve.

Understanding Percentiles and Z Scores

Z scores translate standard deviations from the mean and allow for calculating population percentiles.
A normal curve table provides accurate percentages of scores between any two Z points; for instance, 34% of scores lie between the mean and a Z score of 1.

Calculating Percentiles from Z Scores

To find the percentile corresponding to a Z score:
- Convert the raw score to a Z score, rounding to two decimal places.
- Sketch the normal curve, shading the desired area (to the left or right of the Z score, or between two Z scores).
- Use the normal curve table to identify the exact percentage, rounding down for conservative estimates.

Determining Z Scores from Percentiles

To derive Z scores from a given percentile:
- Draw a normal curve and shade the approximate area representing the target percentile.
- Utilize the normal curve table to find the precise Z score.
- Convert Z score back to raw score when needed, allowing for practical applications in real scenarios.

Description

Test your understanding of the normal distribution with these flashcards. Learn key concepts related to the normal curve, including its properties and significance in psychology. Mastering these terms will enhance your grasp of statistical analysis.