Statistics: Section 2.2

The​ _________________ is the difference between consecutive lower class limits.

class width

Classes

are categories into which data is grouped.

Histogram

is constructed by drawing rectangles for each class of data. The height of each rectangle is the frequency or relative frequency of the class. The width of each rectangle is the same and the rectangles touch each other.

Select the correct choices that complete the sentence below. The​ ______ class limit is the smallest value within the class and the​ ______ class limit is the largest value within the class.

lower;upper

Class width

the difference between consecutive lower class limits Class width= largest data value-smallest data value/number of classes

Uniform distribution

the frequency of each value of the variable is evenly spread out across the values of the variable. The histogram down the middle, right, and left sides are symmetrical

Bell shaped distribution

the highest frequency occurs in the middle and frequencies tail off to the left and right of the middle ( the graph looks like a profile of a bell)

Time series plot

Obtained by plotting the time in which a variable is measured on the horizontal axis and the corresponding value of the variable on the vertical axis. Line segments are then drawn connecting the points.

Upper class limit

the largest value with thin the class

Lower class limit

the smallest value with thin the class

Skewed left

the tail to the left of the peak is longer than the tail to the right of the peak

Skewed right

the tail to the right of the peak is longer than the tail to the left of the peak

Time series data

the value of a variable is measured at different points in time

For IQ scores of students​, state whether you would expect a histogram of the data to be​ bell-shaped, uniform, skewed​ left, or skewed right.

Bell shaped

Steam and leaf plot

Is another way to represent quantitative data graphically

To predict future enrollment in a school​ district, fifty households within the district were​ sampled, and asked to disclose the number of children under the age of five living in the household. The results of the survey are presented in the table. Complete parts​ (a) through​ (c) below.

(a) Construct a relative frequency distribution of the data. Number of Children under 5 Relative Frequency 0 0.28 1 0.3 2 0.28 3 0.1 4 0.04 ​(b) What percentage of households has two children under the age of​ 5? 28​% c) What percentage of households has one or two children under the age of​ 5? 58​%

Why​ shouldn't classes overlap when summarizing continuous data in a frequency or relative frequency​ distribution?

Classes​ shouldn't overlap so there is no confusion as to which class an observation belongs.

Open ended

if the first class has no lower class limit or the last class has no upper class limit