Flashcards in Chap 4 The Normal Distribution Deck (22):

1

## Asymptotic

### When the ends, or "tails", of a distribution never intersect with the x-axis; they extend indefinitely.

2

## Bell Curve

### The common term for a normal distribution. It is called a bell curve because of its bell like shape.

3

## Biased

### When a sample is not selected randomly, it may be a biased sample. A sample is biased when the members are selected in a way that systematically over represents some segment of the population and underrepresents other segments

4

## Convenience Sampling

### When a sample is selected because it is convenient rather then random.

5

## Descriptive Statistics

### Statistics that describe the characteristics of a given sample or population. These statistics are only meant to describe the characteristics of those from whom data were collected.

6

## Inferential Statistics

### Statistics generated from sample data that were used to make inferences about the characteristics of the population the sample is alleged to represent.

7

## Kurtosis

### The shape of a distribution of scores in terms of its flatness or peakedness.

8

## Leptokurtic

### A term regarding the shape of a distribution. A leptokurtic distribution is one with a higher peak and thinner walls.

9

## Negatively Skewed

### When a tail of a distribution of scores extends toward the lower end of the distribution.

10

## Normal Distribution

### A bell-shaped frequency distribution of scores that has the mean, median, and mode in the middle of the distribution and is symmetrical and asymptotic

11

## Null hypothesis

### A hypothesis that there is no effect

12

## Platykurtic

### A term regarding the shape of a distribution. A platykurtic distribution is one with a lower peak and thicker tails

13

## Population

### A group from which data is collected or a sample is selected. the population encompasses the entire group for which the data are alleged to apply.

14

## Positively Skewed

### When the tail of the distribution os scores extends towards the upper end of the distribution

15

## Probability

### The likelihood of an event occurring

16

## Random Sampling

### A method of selecting a sample in which every member of the population has a equal chance of being selected.

17

## Representative Sampling

###
A method of selecting a sample in which members are purposely selected to create a sample that represents the population on the same characteristic(s) of interest.

e.g. when a sample is selected to have the same percentages of various ethnic groups as the larger population.

18

## Sample

### An individual or group, selected from a population, from whom data are collected.

19

## Skew

### The degree to which a distribution of scores deviates from the normal in terms of asymmetrical extension of the tails.

20

## Symmetrical

### When a distribution has the same shape on either side of the median

21

## Theoretical Distribtution

### A distribution based on statistical probabilities rather than empirical data

22