Exam 3

Question 1

What is an appropriate measure to summarize ordinal data

Answer 1

Median

Question 2

When a line graph is employed to represent the number of subjects who received each possible score on a variable, this graph is called a frequency ____\

Answer 2

Polygon

Question 3

What is the difference between descriptive and inferential statistics?

Answer 3

Descriptive statistics summarize data

Inferential statistics determine the probability that results are due to chance

Question 4

If you were to graph the results of tatste test between two different types of beverages, the type of beverage w hod appear on the

Answer 4

Horizontal axis

Question 5

What would be an appropriate measure of centeral tendency to summarize interval data

Answer 5

Mean median and mode

Question 6

In a _____ a separate and distinct _____is drawn to represent the number of people who received a possible score

Answer 6

Bar graph

Bar

Question 7

The standard deviation would be an appropriate measure of variability only if the variable is measured on a _____ scale

Answer 7

Interval

Question 8

In a survey examining the number of third vs 6th grade students who buy their lunch at school, the most appropriate description of the results would be to

Answer 8

Compare group percentages

Question 9

A researcher wants to graph the results of a study that examined of food consumption affected preference for a movie. In This example, the preference for the movie should appear ___\

Answer 9

On the vertical axis

Question 10

Example of histograms or frequency polygons

Answer 10

“clustered column” (Excel) or line graphs

Question 11

Sampling error

Answer 11

When you only have a sample and not the entire population. This can result in skewed values

Question 12

Statistic vs parameter

Answer 12

Statistic- characteristic of a small part of the population, i.e. sample.

parameter-fixed measure which describes the target population.

The statistic is a variable and known number which depend on the sample of the population while the parameter is a fixed and unknown numerical value.

Question 13

Descriptive statistics

Answer 13

uses the data to provide descriptions of the population, either through nu

Question 14

Inferential statistics

Answer 14

makes inferences and predictions about a population based on a sample of data taken from the population in question.

Question 15

3 characteristics that completely describe a distribution:

Answer 15

Shape, central tendency & variability

Question 16

Normal distribution shape

Answer 16

Symmetrical. Bell curve

Question 17

Histogram/frequency polygon chart shape

Answer 17

Skewedness. Can be positive to negative

Question 18

Frequency distribution

Answer 18

Shows number of instances in which a variable takes each of its possible values.

Question 19

Central Tendency

Answer 19

– It is the score that indicates where on the scale the distribution is located
– It indicates the value of the variable around which most of the scores are found.
– A measure of central tendency is usually (but not always) near the center of the distribution.

Question 20

Population

Answer 20

μ, N

Question 21

Sample

Answer 21

n

_
X(or M)

Question 22

Mode

Answer 22

Score that shows the most

Can be used on all for scales of measurement measurement (nominal, ordinal, interval, ratio)

Only one that can be used for nominal dependent variables

Question 23

What is the only central tendency that can be used for nominal dependent variables

Answer 23

Mode

Question 24

What can be used on all four scales of measurement

Answer 24

Mode

Question 25

How do bar graphs differ from line graphs or histograms

Answer 25

Line graphs and histograms do not show frequency distribution Histograms and line graphs are used for ratio and interval data

Question 26

Median

Answer 26

The median is the score below which half of the scores in the distribution fall; it is the 50th percentile

Question 27

“I make less money than average, but (almost) more money than most. What am I?”

Answer 27

The median

Question 28

When can the median be used

Answer 28

ordinal, interval, ratio

Question 29

When is the median most useful

Answer 29

When describing skewed data

Question 30

In highly skewed data, the _____most accurately reflects the center of the scores.

Answer 30

Median

Question 31

Problems with the Median

Answer 31

it is based on counts of scores, not on the value of the scores.

Question 32

mean

Answer 32

Average score located at the exact mathematical center of a distribution

Question 33

Limitations of the Mean

Answer 33

Since the mean requires variables with equal intervals it can only be used on interval or ratio scales of measurement extremely sensitive to extreme scores

Question 34

What central tendency method can only be used for interval or ratio data

Answer 34

The mean

Question 35

What are most inferential statistics based off of

Answer 35

The mean

Question 36

Variability

Answer 36

How different or spread out scores are in a distribution

Question 37

Ways to measure variability

Answer 37

Range Sum/average of deviations Sum/average of deviations squared Variance (population & sample) Standard deviation (population & sample)

Question 38

Range

Answer 38

The simplest, and least informative, measure of variability Range = Highest Score – Lowest Score

Question 39

Problems with the range

Answer 39

Two different sets of numbers can have the same range, even though they are very different. It does not take into account all of the information that is available in the entire set of scores.

Question 40

When is the Range used?

Answer 40

In descriptive manners. | Ex-describing age. The age ranged from 14-77

Question 41

Problems with Deviations from | the Mean. What to do about it

Answer 41

Average of the deviations always equals zero What to do about it - The sum of squared deviations from the mean” or “Sum of Squares” (SS)

Question 42

Deviation from the mean

Answer 42

X-average

Question 43

Formulas for variance

Answer 43

“definitional” or “derivational” “computational” or “raw score” “calculational”(book)

Question 44

Problem with variance

Answer 44

Variance is unrealistically large, and is interpreted in squared units – To get back to regular or “standard” units we take the square root after calculating the average squared deviation score (aka, variance)

Question 45

Standard Deviation

Answer 45

average distance from the mean

Question 46

Standard deviation is the same as...

Answer 46

Squared deviation

Question 47

Degrees of freedom

Answer 47

For samples, instead of (N), use (n-1) in the denominator

Question 48

What’s the issue with variance of a sample?

Answer 48

the variance of a sample is a little too small for (aka, underestimates) the actual population variance

Question 49

What is the z score of the top 5% or less

Answer 49

1.65

Question 50

What’s the z score for being in either the top or bottom 5%

Answer 50

1.96

Question 51

Standardization

Answer 51

the process of transforming a variable to one with a mean of 0 and a standard deviation of 1.

Question 52

why do we want to know z scores

Answer 52

we want to know where something where it is located in the distribution of scores. (I.e., how far away a score is from the mean) tells you the exact location of the original X value within a distribution.

Question 53

standardized | distributions and z scores

Answer 53

z scores help standardize distribution by allowing comparison of different distribution scores

Question 54

Binomial Distribution

Answer 54

These distributions tell us the probability for a specific number of “successes” to happen, given a probability of success and number of trials. binomial distributions tell us the results of only two possible outcomes: success or failure. An example of this is flipping a coin, which can only result in heads or tails.

Question 55

% of scores lie between 0 and 1 SDs | above the mean.

Answer 55

34.13%

Question 56

% of scores are between 1 and 2 SDs | above the mean.

Answer 56

13.59%

Question 57

% of scores are between 2 and 3 SDs | above the mean.

Answer 57

2.15%

Question 58

% of scores are more than 3 SDs above the | mean.

Answer 58

0.13%

Question 59

Alpha level

Answer 59

This is the probability level for significance.

Question 60

Sampling distribution

Answer 60

shows every possible result a statistic can take in every possible sample from a population and how often each result happens

Question 61

In a perfect relationship between two variables, r squared would be

Answer 61

Equal to 1.00