# Statistics ch2

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Statistics ch2

## 1. Qualitative ( categories )

### 1.1. Bar graph

1.1.1. Represents the data by using vertical or horizontal bars whose heights or lengths represents the freq. of the data

1.1.1.1. The distance between columns have to be equal

1.1.1.2. No need to arrange

1.1.1.3. Number of classes ? Count classes / عد كم فئة وليس جمع

1.1.1.4. Sample size

1.1.1.4.1. Sum of coulmns

### 1.2. Pareto charts

1.2.1. Used to represent a freq. dist. For a categorical variable

1.2.1.1. Vertical; number

1.2.1.2. Horizontal; category

1.2.1.3. Bars corresponding to the freq.

1.2.1.4. Arrange data from the largest to the smallest

## 2. Quantitative

### 2.1. Table

2.1.1. Grouped freq. dist.

2.1.1.1. Range = upper - lower > 11

2.1.2. Ungrouped freq. dist.

2.1.2.1. Upper - lower < = 11

### 2.2. Graph

2.2.1. Histogram

2.2.1.1. A graph that display data by using contiguous vertical bars

2.2.1.1.1. Horizontal ; Class boundaries

2.2.1.1.2. Vertical ; Freq.

2.2.1.1.3. Mid point

2.2.1.1.4. Total number of value ( sample size )

2.2.1.1.5. Number of classes

2.2.1.1.6. Width

2.2.1.1.7. Percent

2.2.2. Freq. polygon

2.2.2.1. A graph that display data by using line that connect points plotted for the freq. at the mid points of classes .

2.2.2.1.1. Horizontal; Midpoint

2.2.2.1.2. Vertical ; Freq.

2.2.2.1.3. Width

2.2.2.1.4. Begin and end on the x- axis

2.2.2.1.5. Begin from zero

2.2.2.1.6. Sample size

2.2.2.1.7. Sample size

2.2.3. Ogive

2.2.3.1. A graph that represents the cumulative freq. for the classes in a freq. dist.

2.2.3.1.1. Horizontal; Class boundaries

2.2.3.1.2. Vertical ; Cumulative freq.

2.2.3.1.3. Always closed at zero

2.2.3.1.4. Always increased and end at the highest point

2.2.3.1.5. Sample size

2.2.4. Relative freq.

2.2.4.1. Freq / total , sum of relatives = 1

2.2.5. A stem and leaf plot

2.2.5.1. A data plot the uses part of the data value as the stem and part of the data value as the leaf to form groups or classes

2.2.5.1.1. No gaps

2.2.5.1.2. If there is no data values in a class you should write the stem number and leave the leaf row blank

2.2.6. The time series

2.2.6.1. Represents data that occur over a specific period of time / مثال ارباح الشركة خلال الخمس سنوات الماضية