descriptive statistics

Question 1

what does descriptive statistics mean ?

Answer 1

summarization of data in the means of numbers

Question 2

what are the most common use of measure of descriptive statistics ?

Answer 2

measure of central tendency

measure of dispersion

Question 3

what are the most commonly used measure of central tendency ?

Answer 3

the mean or the average
the median
the mode

Question 4

what is the arithmetic mean or average ?

Answer 4

sum of all the values divided by the total number of values

Question 5

what are the advantage of the arithmetic mean ?

Answer 5

1. simplicity
2. uniqueness
3. takes into account all values of the data

Question 6

what are the disadvantges of the mean ?

Answer 6

distorted by extreme values

cannot be used for qualitative data

Question 7

what is the median ?

Answer 7

the numbers are put into order from smallest to larger and the number in the middle is the median

Question 8

if there is an odd number of numbers how is the median calculated ?

Answer 8

n+1
___
2

Question 9

what are the advantages of the median ?

Answer 9

simplicity
uniqueness
not affected by extreme values like the mean

Question 10

what are the disadvantages of the median ?

Answer 10

doesn’t take into account all values of the sample

Question 11

what is the mode ?

Answer 11

is the number with the highest frequency in the set of values

Question 12

what are the advantages of the mode ?

Answer 12

1. simplicity
   2 .the mode is not affected by extreme values
2. used for both quantitative and qualitative data

Question 13

what are the disadvantages of the mode ?

Answer 13

1. doesn’t take into account all values of the sample
   2 .may not be a mode for the data
   3 .might be more than one mode for a set of data

Question 14

what does the measure of dispersion mean ?

Answer 14

shows the variability of a set of data

Question 15

what are the different ways to measure dispersion ?

Answer 15

the range
variance
standard deviation
coefficient of variation

Question 16

what is the range ?

Answer 16

the difference between the largest and the smallest value

Question 17

what is the best measure of central tendency ?

Answer 17

the mean

Question 18

what is the most common way to find the dispersion ?

Answer 18

the standard deviation

Question 19

what is the relationship between the variance and the mean ?

Answer 19

1. variance of the data is small when the observations are close to the mean
2. the variance of the data is large when the observations are far from the mean

Question 20

what is the variance when all the values are the same ?

Answer 20

the variance is 0

Question 21

what is the variance ?

Answer 21

how close on average the values of a variable are to the arithmetic mean

Question 22

what is the coefficient of variation ?

Answer 22

the comparison between two variables

Question 23

how is the coeffecient of the variable calculated ?

Answer 23

CV=SD/mean x 100%

Question 24

what are the different numeric presentations of qualitative variables ?

Answer 24

count
proportion
ratio
rate

Question 25

when is it most appropriate to use the count ?

Answer 25

when there are difficulties relating the observation to a population

Question 26

what does the proportion describe ?

Answer 26

is a fraction in which the numerator is included in the denominator

Question 27

what does the ratio describe ?

Answer 27

fraction in which the numerator is not included in the denominator

Question 28

what are the different types of tables ?

Answer 28

simple frequency tables 
contingency table ( cross tabulation )

Question 29

what are the types of graphs that can be drawn for qualitative data ?

Answer 29

pie chart

bar chart

Question 30

what are the types of graphs that can be drawn for quantitative data ?

Answer 30

histogram

scatter plot