Module 2: Descriptie Statistics

Question 1

Descriptive statistics

Answer 1

Use numerical & visual summaries to describe & illustrate a data set

Question 2

Variable

Answer 2

A measurement made on each individual case (unit) in a population (if we measure each persons weight, in the entire population, then “weight” would be a variable

Question 3

Quantitative variable

Answer 3

Means something mathematically (Weight, height, age, number of products sold, etc.)

Question 4

Quantitative - discrete

Answer 4

Countable,like number of products sold (something that is countable)

Question 5

Quantitative-continuous

Answer 5

Not countable, like weight, height

Question 6

Qualitative variables

Answer 6

Categorical variable, can be categorized (Colours, customer satisfaction level, suit of cards, etc.)

Question 7

Qualitative-ordinal

Answer 7

Has an order/ranking/hierarchy to it, like satisfaction level (order matters)

Question 8

Qualitative-normative

Answer 8

Also called nominal: no natural order, like colours (order doesn’t matter)

Question 9

Measures of central tendancy

Answer 9

A measurement of the centre or typical value of a data set

Question 10

Skewed

Answer 10

A sample, data set, or population is skewed if it contains extreme values

Question 11

Positive skew (skewed to the right)

Answer 11

An extreme value on the far right

Question 12

Negative skew (left skewed)

Answer 12

Has an extreme value on the far left hand side of the number line

Question 13

Weighted mean

Answer 13

Each observation may have a different level of importance

Question 14

The median

Answer 14

The middle value of a data set

Question 15

The mode

Answer 15

The most frequently occurring value

Question 16

Bimodal

Answer 16

When there are 2 modes (10,11,11,12,12,13) - 11 and 12

Question 17

Trimodal

Answer 17

3 modes

Question 18

Multimodal

Answer 18

More than 3 modes

Question 19

Measures of variation

Answer 19

A measure of the amount of spread of the data set ex:the range, the mean absolute deviation, the variance, the standard deviation

Question 20

Range

Answer 20

The difference b/w the maximum and minimum value of a data set - range=max(x) - min(x)

Question 21

Mean absolute deviation (MAD)

Answer 21

The average value of the difference, in absolute value, of each observation from the mean EXCEL: avedev()

Question 22

Sample deviation

Answer 22

The difference b/w a sample value Xi and the sample mean X-

Question 23

Variance

Answer 23

The average squared deviation of each observation from the mean EXCEL: var.p()

Question 24

Standard deviation

Answer 24

The square root of the sample variance EXCEL: sample- stdev.s() and population- stdev.p()

Question 25

Extreme value

Answer 25

An observation that lies more than 3 standard deviations above or below the mean