2.2 histograms & frequency distributions for quantative data

Question 1

frequency distribution for continuous quantitative data

Answer 1

we divide the data into class because they have no natural categories

Question 2

classes

Answer 2

intervals of equal width that cover all values that observed in the data set

Question 3

lower class limit

Answer 3

smallest value that appears in the class

Question 4

upper class limit

Answer 4

largest value that can appear in the class

Question 5

class width

Answer 5

difference between consecutive lower class limits

Question 6

guidelines for choosing classes

Answer 6

every observation must fall into one of the classes, classes cant overlap, classes have to have equal width, there should be no gaps between classes even if there are no observations in a class, it needs to be included in the frequency districution

Question 7

constructing a frequency distribution

Answer 7

1. choose a class width 2. pick a lower class limit for the first class which should be a convenient # that is slightly less than the minimum data value, 3. compute the lower limit for the second class by adding the class width to the lower limit for the first class, 4. compute the lower limits for each of the remaining classes by adding the class width to the lower limit fo the preceding class. stop when the largest data value is included in a class 5. count the number of observations in each class and construct the frequency distribution

Question 8

relative frequency distribution aka frequency distribution

Answer 8

frequency/ sum of all frequencies

Question 9

histogram

Answer 9

a bar graph that displays the relative frequency distribution with its width equal to the class width

Question 10

frequency vs relative frequency

Answer 10

the vertical axis for frequency is a whole number and for relative its a decimal

Question 11

choosing the number of classes

Answer 11

not too little and not too much; too few lacks details and too much obscures the main features of the data

Question 12

histograms on ti-84 plus

Answer 12

enter data in L1; press 2nd,Y=, then 1 to access plot 1 menu. select On and the histogram plot type; press zoom, 9 to view the plot

Question 13

skewed to the right, or positively skewed

Answer 13

a histogram with a long right-hand tail

Question 14

skewed to the left, or negatively skewed

Answer 14

histogram with a long left- hand tail

Question 15

symmetric

Answer 15

if the histograms’ right have is a mirror image of its left half

Question 16

bell-shaped

Answer 16

a symmetric histogram wth a peak in the middle

Question 17

uniformly distributed

Answer 17

a symmetric histogram in which all classes have about equal frequencies

Question 18

mode

Answer 18

a peak or high point of a histogram

Question 19

unimodal

Answer 19

has only one mode

Question 20

bimodal

Answer 20

has two clear and distinct modes