Chap 4 The Normal Distribution Flashcards Preview

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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

Unimodal

A distribution that has a single mode.