Summarising Data

Question 1

Descriptive statistics

Answer 1

Techniques that help describe a set of data

Question 2

Inferential statisitcs

Answer 2

Methods that use the limited

information from samples to answer general questions about populations

Question 3

Statistic

Answer 3

A summary value that describes a sample. A common example of a statistic is the average score for a sample.

Question 4

Parameters

Answer 4

A summary value that describes a population. A common example of a parameter is the average score for a population.

Question 5

Frequency distribution

Answer 5

A tabulation of the number of individuals in each category on the scale of measurement. A frequency distribution displays two sets of information:

1. The set of categories that make up the scale of measurement.
2. The number of individuals with scores in each of the categories

Question 6

Descriptive statistics

Answer 6

Methods that help researchers organize, summarize, and simplify the results obtained from research studies

Question 7

Inferential statistics

Answer 7

Methods that use the results obtained from samples to help make generalizations about populations

Question 8

Histogram

Answer 8

A histogram shows a bar above each score so that the height of the bar indicates the frequency of occurrence for that particular score. The bars for adjacent scores touch each other

Question 9

Polygon

Answer 9

A polygon shows a point above each score so that the height of the point indicates the frequency. Straight lines connect the points, and additional straight lines are drawn down to the horizontal axis at each end to complete the figure

Question 10

Bar graph

Answer 10

A bar graph is like a histogram except that a space is left between adjacent bars

Question 11

Central tendency

Answer 11

Central tendency is a statistical measure that identifies a single score that defines the center of a distribution. The goal of central tendency is to identify the value that is most typical or most representative of the entire group

Question 12

Mean

Answer 12

The mean is the most commonly used measure of central tendency. The mean is computed by adding the scores and dividing the sum by the number of individuals

Question 13

Median

Answer 13

The median is the score that divides a distribution in half, so that 50% of
the individuals have scores that are less than or equal to the median. Usually, the median is used for data sets in which the mean does not provide a good representative value

Question 14

Mode

Answer 14

The mode is the score or category with the greatest frequency. In a frequency distribution graph, the mode identifies the location of the peak (highest point) in the distribution

Question 15

Variance

Answer 15

The calculation of standard deviation begins by computing the average squared distance from the mean. This average squared value is called variance

Question 16

Standard deviation

Answer 16

Square root of the variance and provides a measure of variability by describing the average distance from the mean

Question 17

Degrees of freedom

Answer 17

n - 1, where n is the number of scores in the sample.

the average squared distance for a sample is computed by dividing the sum of the squared distances by n - 1

Question 18

Normal curve

Answer 18

A symmetrical, bell-shaped frequency polygon representing a normal distribution.

Question 19

Normal distribution

Answer 19

A theoretical frequency distribution that has certain special characteristics

Question 20

Kurtosis

Answer 20

How flat or peaked a normal distribution is

Question 21

Mesokurtic

Answer 21

Normal curves that have peaks of medium height and distributions that are moderate in breadth

Question 22

Leptokurtic

Answer 22

Normal curves that are tall and thin, with only a few scores in the middle of the distribution having a high frequency

Question 23

Platykurtic

Answer 23

Normal curves that are short and more dispersed (broader), when there are many scores around the middle score that all have a similar frequency

Question 24

Positively skewed distribution

Answer 24

A distribution in which the peak is to the left of the centre point, and the tail extends toward the right, or in the positive direction

Question 25

Negatively skewed distribution

Answer 25

A distribution in which the peak is to the right of the centre point, and the tail extends toward the left, or in the negative direction

Question 26

Z-score / standard score

Answer 26

A measure of how many standard deviation units an individual raw score falls from the mean of the distribution

Question 27

Standard normal distribution

Answer 27

A normal distribution with a mean of 0 and a standard deviation of 1

Question 28

Probability

Answer 28

The expected relative frequency of a particular outcome

Question 29

Percentile rank

Answer 29

A score that indicates the percentage of people who scored at or below a given raw score