MEASURES OF CENTRAL TENDENCY, DISPERSION, AND LOCATION

Question 1

called measures of central location.
The common measures are the Mean, Median and Mode. These are all valid measures of central
tendency, but depending on different conditions, some measures of central tendency become more
appropriate to use than others

Answer 1

MEASURES OF CENTRAL TENDENCY

Question 2

It is the most popular and well known measure of central tendency. It can be used with both
discrete and continuous data. An important property of the mean is that it includes every value
in your data set as part of the calculation

Answer 2

MEAN (AVERAGE)

Question 3

susceptible to the influence of outliers. For
example, consider the wages of staff at a factory below:

Answer 3

When not to use the mean?

Question 4

 The middle score for a set of data that has been arranged in order of magnitude.
 It is less affected by outliers and skewed data.

Answer 4

MEDIAN

Question 5

most frequent score in our data set
used for categorical data where we wish to know which is the most common category

Answer 5

MODE

Question 6

When we have two or more values that share the highest frequency
When the most common mark is far away from the rest of the data in the data set

Answer 6

Problems when using mode

Question 7

measures of Spread
 Also called as measure of dispersion.
 It is used to describe the variability in a sample or population.
 It is used in conjunction with a measure of central tendency.
 A measure of spread gives us an idea of how well the mean, for example, represents the
data.

Answer 7

Measures of Spread

Question 8

It is the measure of the spread of scores within a set of data
measures how concentrated the data are around the mean. It is used in conjunction with the mean to
summarize continuous data. It is appropriate only when the continuous data is not significantly
skewed or has outliers

Answer 8

Standard Deviation

Question 9

Another method for calculating the deviation of a group of scores from the mean

Answer 9

Variance

Question 10

difference between the largest score in the set of data and the smallest

Answer 10

Range

Question 11

 you have ordinal data or
 you are presenting your results to people with little or no knowledge of statistics

Answer 11

The range is used when:

Question 12

It depends on only two scores in the set of data, XL and XS
 Two very different sets of data can have the same range:

Answer 12

The range is rarely used in scientific work as it is fairly insensitive

Question 13

always expressed in percentage (%). It shows Variation
Relative to the mean and is used to compare two or more groups.

Answer 13

Coefficient of Variation

Question 14

Percentile, Quartile, and Deciles

Answer 14

MEASURES OF LOCATION OR POSITION

Question 15

 Numerical measures that give the relative position of a data value relative to the entire data
set.
 Divide an array (raw data arranged in increasing or decreasing order of magnitude) into 100
equal parts.
 The kth percentile, denoted as Pk, is the data value in the data set that separates the bottom k%
of the data from the top (100-k)%.

Answer 15

Percentiles

Question 16

 Divide an array into ten equal parts, each part having ten percent of the distribution of the
data values, denoted by Dk.
 The 1st decile is the 10th percentile; the 2nd decile is the 20th percentile and so on

Answer 16

Deciles

Question 17

 Divide an array into four equal parts, each part having 25% of the distribution of the data
values, denoted by Qk.
 The 1st quartile is the 25th percentile, the 2nd quartile is the 50th percentile, also the median
and the 3rd quartile is the 75th percentile

Answer 17

Quartiles

Question 18

A display of statistical information that uses rectangles to show the frequency of data
items in successive numerical intervals of equal size

Answer 18

Histogram

Question 19

A data point that differs significantly from other observations.

Answer 19

Outliers