Dr. Asawer A. Alwasiti

 Chapter one: Introduction  Chapter two: Frequency Distribution  Chapter Three: Measures of Central Tendency  Chapter Four: Measures of Dispersion  Chapter Five: The Polynomial Distribution  Chapter Six: Curve Fitting  Chapter Seven: Correlation Theory

 Statistics: is concerned with scientific methods for collecting, organizing, summarizing, presenting and analyzing data as well as drawing valid conclusions and making reasonable decisions.  Types of data:  Quantitative data : are those that represent the quantity or amount of something, measured on a numerical scales. For example; the power frequency  Qualitative data: it’s the data that can only classified i.e. posses no numerical representation  Population: refers to all the persons, objects, source or measurements under consideration, or it is a data set that is our target of interest.  Sample: refers to any portion of the population

 Descriptive Statistics: used to organize, summarize and describe measures of sample. It uses numbers to summarize information which is known about some situation.  Inductive (inference) statistics: are used to predict population parameters from sample measures.  Variables: is a symbol such as X, Y,H…. which can assume any of the prescribed set of values. It contains qualitative and quantitative variables  Continuous variable: can theoretically assume any value between two given values depending on accuracy of measurements  Discrete variable: all data can be obtained from counting  Parameter: the measures which describe population characteristics. 

 Example:  The reliability of computer system is measured in terms of life length of a specific hardware component (e.g hard disk life). To estimate the reliability of a particular system, 100 computer component are tested until they fail, under their life length are recorded.  What is the population of interest?  What is the sample?  Are the data are qualitative or quantitative?  How could the sample information be used to estimate the reliability of the computer system? 

 Qualitative Data They are usually achieved using Bar graph or Pie chart  Bar graph: the category (class) of the qualitative variable is represented by Bar graph in which the height of each bar is either the class frequency, class relative frequency or class percentage.  Pie chart: the category (class) of the quantitative variable is represented by Pie chart. The size of each slice is proportional to the class relative frequency.  Pareto diagram: a bar graph with the category (class) of the qualitative variable arranged by height in descending order from left to right.

 Example:  Group of researchers investigating the safety of nuclear power reactors and the hazard of using energy, they discovered 45 energy related accident worldwide since1977 that resulted in multi factories as: categoryfrequency Coal mine collapse7 Dam frailer4 Gas explosion28 lightning1 Nuclear reactor1 Oil fire4 total45

 Quantitative Data  It can be represented in graphical or numerical way  Graphical representation Quantitative Data can be represented graphically by Histogram  Frequency distribution  Raw data: are collected data which have been collected numerically  Array: arranged of raw data in ascending or descending order.  Range: the difference between the largest and smallest value  Frequency distribution: a table arrangement of data by classes together with the corresponding class frequencies.  Class interval: A symbol defining the class.  Class mark: is the mid point of the class interval  Formation of frequency distribution:  Determine the largest and smallest observation  Take total width = range + 1 unit in the last significant digit  Dived total width in 5-20 class of equal width  Calculate class width, interval and class mark  Calculate frequencies   Histogram  Graphical representation of frequency distribution consist of a set of rectangular having:  Basis with centers at class marks and lengths equal to the class width  Area proportional to class frequencies   Frequency polygon  Formed by connecting the mid points of the tops of the rectangular in the histogram  Relative frequency  Is the frequency of the class divided by the total frequency and expressed as a percentage

 Example  The pH level of drilling mud of well that determined within 24 hr is shown in table below, make the frequency distribution table and graph the data  Example  The viscosity of 40 sample of drilling mud measured in cp is shown below.  Represent them in frequency table and with histogram