Statistics I -chapter 2

Why should the number of classes in a frequency distribution be between 5 and 20?

In order to detect any patterns

Ogive

Is a cumulative frequency graph that displays cumulative frequencies

Integer Data- class limits and boundaries differ by

0.5

Find class width for min=10, max=96, 6 classes....and lower and upper class limits

96-10=86....(range)....divide by 6 and round up =15... Lower class limits 10,25,40,55,70,85. Upper class limits 24,39,54,69,84,99

After constructing a relative frequency distribution summarizing IQ scores of college​ students, what should be the sum of the relative​ frequencies?

If percentages are​ used, the sum should be​ 100%. If proportions are​ used, the sum should be 1.

Class limits

Least and greatest numbers that can belong to a class

Range

Minimum subtracted from maximum

Upper limit for first class is

One less than the lower limit of second class

What are some benefits of representing DATA SETS using frequency distributions?

Organizing the data into a frequency distribution can make patterns within the data more evident.

To find class's upper limits, find first class then add min number to each.....example- min=9, max=69, 7 classes....lower limits for first class is 9, second is 18 (9+9)....upper limit is 18-1=17....

Other classes (add 9) is 17, 26, 35, 44, 53, 62, 71

To find class width

Subtract minimum from maximum and divide by number of classes...(round to nearest whole number).

To find lower limits of all classes (min=9, max=69, 7 classes).....

Take first min, which is 9 then add 9 to each class for all 7 classes.....answer is 9,18,27,36,45,54,63

Relative Frequency of a class

is the percentage of the data that falls in that class

Class width

is the range (max.-min.) divided by number of classes.....round up to nearest whole number

The difference between the maximum and minimum data entries is called the

range

The class width is

the distance between lower (or upper) limits of consecutive classes.

The midpoint of a class is

the sum of its lower and upper limits divided by two

In a Frequency distribution,

class width is the distance between the lower and upper limits of consecutive classes.

frequency polygon

displays class frequencies

Each class has an upper class limit, which

Is the greatest number that can belong to the class.

Each class has a lower class limit, which

Is the least number that can belong to the class.

Cumulative frequency of a class

Is the sum of the frequencies of that class and all previous classes

What are some benefits of using GRAPHS of frequency distributions?

It can be easier to identify patterns of a data set by looking at a graph of the frequency distribution.

Class Boundaries

are the numbers that separate classes without forming gaps between them; they ensure that consecutive bars of a histogram touch.