Test One - Chapters 1-6

Question 1

Variability

Answer 1

The degree to which scores in a distribution are spread out

How much distance to expect between one score and another

Question 2

Standard Deviation

Answer 2

The distance between each score and the mean
The average distance from the mean

Most commonly used measure of variability

Question 3

Standard Deviation for Samples

Answer 3

Samples are consistently less variable than their population
Sample variability is a biased estimate of population variability
Consistently underestimates the population value

Question 4

Descriptive Statistics

Answer 4

Organizes and summarizes info from a research study

Question 5

Inferential Statistics

Answer 5

Determines what conclusions can be drawn from a research study
- use the sample data as the basis for answering questions about the population
> to accomplish this, typically built around the concept of probability

Question 6

Statistics

Answer 6

A set of mathematical procedures for organizing, summarizing and interpreting info

Question 7

Parameter

Answer 7

A value that describes a population

i.e. 65% are female

Question 8

Statistic

Answer 8

A value that describes a sample

Question 9

Sampling Error

Answer 9

Discrepancy between the sample and the population

Unpredictable, random differences that exist between samples

Question 10

Operational Definition

Answer 10

A statement of procedures (operations) used to define research variables

Question 11

Discrete Variable

Answer 11

Variable with separate, indivisible categories

Question 12

Continuous Variable

Answer 12

Infinite number of value between two observed values

Question 13

Deviation Score

Answer 13

x-u

u= mew

Sum of deviation scores should always be 0

Question 14

Nominal Scale

Answer 14

classify individuals into categories that have different names
eg. gender, university, etc.

direction of difference = no
magnitude of difference = no

Question 15

Ordinal Scale

Answer 15

set of categories organised in an ordered sequence
eg. t-shirt size, ranked place in a race, class, etc.

direction of difference = yes
magnitude of difference = no

Question 16

Interval Scale

Answer 16

categories form a series of intervals all of the exact same size
eg. temperature or golf scores

• arbitrary zero point -> zero represents the presence of something

Question 17

Ratio Scale

Answer 17

categories form a series of intervals all of the exact same size
eg. distance, time, weight

• absolute zero point -> zero represents the absence

Question 18

N v.s. n

Answer 18

N = total number of scores in a population
n = total number of scores in a sample

Question 19

u (mew) v.s. M

Answer 19

u (mew) = mean of a population
i.e. Σx/N

M = mean of a sample
i.e Σx/n

Question 20

Order of Operations

Answer 20

(1) parentheses (_____)
(2) squaring
(3) x or /
(4) Σ
(5) +/-

Question 21

Central Tendency

Answer 21

single value that defines the average score
identifies the center of the distribution

no single measure will always produce a central, representative value in every situation

uses mean, median and mode to find “center”

Question 22

Weighted Mean

Answer 22

combining two sets of scores to find the overall mean

*below the 1 and 2 represent the set

Σx1 + Σx2 / n1 + n2

Question 23

Rules of the Mean

Answer 23

changing the value of any score will change the mean

Question 24

Bimodal or Multimodal

Answer 24

two or more modes

Question 25

The Mode is preferred when...

Answer 25

nominal scale of measurement discrete variables describing the shape of the distribution graph

Question 26

The Mean is preferred when...

Answer 26

preferred measure of central tendency

Question 27

The Median is preferred when...

Answer 27

few extreme scores unknown or undetermined scores no upper or lower limit for one category

Question 28

Variability

Answer 28

the degree to which scores in a distribution are spread out how much distance to expect between one score and another

Question 29

Standard Deviation

Answer 29

most commonly used measure of variability the distance between each score and the mean the average distance from the mean

Question 30

σ v.s. s

Answer 30

``` σ = standard deviation for a population s = standard deviation for a sample ```

Question 31

σ²

Answer 31

variance | = SS/N

Question 32

Computational Formula

Answer 32

SS = ΣX2 - (ΣX)2/N

Question 33

Standard Deviation for Samples

Answer 33

samples are consistently less variable than their population sample variability is a biased estimate of population variability consistently underestimates the population value ``` to correct for this do n-1 i.e. sample variance is: s2 = SS/n-1 sample standard deviation is: s = square root of SS/n-1 ```

Question 34

z-Scores

Answer 34

* statistical technique that uses the mean and standard deviation to transform each x-value into a standardized score * tells us exactly where x-values are located in a distribution * sign tells whether the score is above (+) or below (–) the mean * number tells distance (number of standard deviations) from the mean

Question 35

Characteristics of a z-score distribution

Answer 35

* shape of z-score distribution will be the same as the original * each individual score stays in the same position * the mean is always = 0 * the standard deviation is always = 1

Question 36

Probability

Answer 36

For a situation in which several different outcomes are possible, the probability for any specific outcome is defined as a fraction or a proportion of all the possible outcomes. If the possible outcomes are identified as A, B, C, D, and so on, then: probability of A = number of outcomes classified as A / total number of possible outcomes - probability gives us a connection between populations and samples

Question 37

The role of probability in inferential statistics

Answer 37

Probability is used to predict what kind of samples are likely to be obtained from a population. Probability establishes a connection between samples and populations. Inferential statistics rely on this connection when they use sample data as the basis for making conclusions about populations.

Question 38

Simple Random Sample

Answer 38

A simple random sample requires that each individual in the population has an equal chance of being selected.

Question 39

Random Sampling

Answer 39

• each individual in the population has an equal chance of being selected for a sample. p = 1/N • the probabilities must stay constant from one selection to the next if more than one person is selected - sampling with replacement A sample produced by this technique is known as a random sample.

Question 40

Probability and Normal Distribution

Answer 40

* highest frequencies are in the middle (close to the mean) | * lowest frequencies are in the tails (highest and lowest scores)

Question 41

Probability and z-Score Distribution

Answer 41

* percent of scores that fall within each region | * regions on left side of 0 are the same as the right side (symmetrical)