G ENERAL S TATISTICS S TAT 110

معلومات عن أستاذة المادة: أ. جمانه أحمد درويش البريد الإلكتروني: الموقع الإلكتروني: jdarwish.kau.edu.sajdarwish.kau.edu.sa الساعات المكتبية: الأحد - الثلاثاء: الاثنين: 12-1

الكتاب المقرر: "Elementary Statistics a Step by Step Approach", 7 th Edition (2009) Bluman للحصول على عروض المحاضرات: جامعة الملك عبدالعزيز>> الكليات>> كليات الفروع>> كلية العلوم للبنات>> الأقسام العلمية>> قسم الإحصاء>> الملفات>> أخرى>> (محاضرات إحصاء 110+أوراق عمل إحصاء 110)

CHAPTER 1 The Nature of Probability and Statistics

Statistics Descriptive Statistics 1*Collection 2*Organization *Summarization3 4*Presentation of data. EX: The average age of the students is 17 Inferential Statistics 1*Generalizing from samples to populations 2*Estimations 3*Hypothesis testing 4*Relationships 5*Making predictions. EX: The relationship between weight and age. Statistics Statistics: is the science of conducting studies to collect, organize, summarize, analyze and drawing conclusions from data.

Classify each descriptive or inferential (which branch (area) (type) of statistics): ”the average weight of the student is 50 kg”: ……………… “the relationship between smoking and lung cancer”: ……………... “diet high in fruits will lower blood pressure”: ……………… “In 2015, teaching methods will be improved in many Arabic schools ”: ………………

Variable Variable: is characteristic or attribute that can assume different values. Random Variable : Random Variable : variables whose determined by chance.

Population: consists of all subjects (human or otherwise) that are being studied. Sample : is a group of subjects selected from a population

Data: Data: are the values (measure or observation) that the variables can assume. Data set Data set : Collection of data values. Data value (datum) : Data value (datum) : each value in the data set.

1-2:V ARIABLES AND T YPES OF D ATA (Data) Type of variables QualitativeQuantitative DiscreteContinuous

 Quantitative variables : are numerical and can be ordered or ranked. EX: Age,Height, Weight,temperature …..  Qualitative Variables : are variables that can be placed into distinct categories,according to some characteristic or attribute. EX: Gender,Major,Color, Name, Job ……

 Discrete Variables :  Discrete Variables : assume values that can be counted EX: number of children in a family, number of student in classroom……  Continuous Variables  Continuous Variables : assume an infinite number of values between any two specific values. EX: Temperature, Time, Height, Weight, Salary …..

1-2:V ARIABLES AND T YPES OF D ATA Measurement Scales (Level of Measurement) Qualitative NominalOrdinal Quantitative IntervalRatio

 Nominal : classifies data into mutually exclusive, exhausting categories in which no order or ranking can be imposed on the data. EX: Color, Major,Gender  Ordinal : classifies data into categories can be ranked. EX: Grade(A,B,C,D,F), Size( S,M,L,XL)  Interval : ranks data and precise differences between units of measure do exist,however there is no meaningful zero EX: Temperature, IQ test  Ratio: possesses all the characteristics of interval,and there exist a true zero. EX: Height, Weight, Time

* Identify the level of measurement for “ages of students in class”: a) Quantitative b) Continuous c) Ratio d) Interval * ”The number of the players” is an example of which type: a) Ordinal b) Continuous c) Ratio d) Discrete * ”The number of the players” is an example of which level of measurement : a) Ordinal b) Continuous c) Ratio d) Discrete C HOOSE THE CORRECT ANSWER :

* "The temperature of Jeddah city." What is the type of this variable? a) Interval b) Qualitative c) Continuous d) Discrete * "The temperature of Jeddah city." What is the level of measurement of this variable? a) Interval b) Qualitative c) Continuous d) Discrete * "Students’ grades consist of excellent, very good, and good." What is the level of measurement of this variable? a) Nominal b) Ordinal c) Qualitative d) Ratio

* Identify the level of measurement for the marital(زوجي) status of patients in a hospital: a) Ordinal b) Nominal c) Ratio d) Interval * ”The time students spend studying daily” is an example of which type: a) Ordinal b) Continuous c) Ratio d) Discrete

* The level of measurement classifies data into red, blue in which no order can be imposed the data. a) Ordinal b) Nominal c) Ratio d) Interval * The level of measurement classifies data into categories that can be ranked, however precise differences between the ranks do not exist. a) Ordinal b) Continuous c) Ratio d) Discrete

(1-3) Data collection and sampling techniques

 Data can be collected in a variety of ways. One of the most common methods is through the use of surveys.  Surveys can be done by using a variety of methods : - telephone, -mail questionnaires, -personal interviews, surveying records and direct observations.

Sampling techniques Random Sampling Systematic Sampling Stratified Sampling Cluster Sampling Random : random number (chance). Systematic : every kth subject. Stratified :divide population into group called “strata”. (each) Cluster :use intact groups.

1- Random Sampling : 1- Random Sampling : are selected by using chance methods or random numbers. For example: For example: Select random sample of 15 subjects out of 85 subjects, each subject numbered from 1 to Systematic Sampling : are obtained by numbering each value in the population and then selecting the every kth value. 3- Stratified samples: are selected by dividing the population into groups (strata) according to some characteristic and then taking samples from each group. For example : A researcher select a random sample from each gender to check their blood pressure.

4- Cluster samples: are selected by dividing the population into groups an then taking samples of the groups. (large population) For example : In a large school district,all teachers from two building are interviewed to determine whether they believe the students have less homework to do now than in previous years. In the airport

What kind of sampling technique is used: (Random – Systematic – Stratified – Cluster) 1- A researcher selects 20 people from Aziz mall by using random numbers to do a survey. 2- Every seventh customer entering a shopping mall is asked to select her or his favorite store. 3- To determine the average salaries for teachers in a school district, all teachers from three schools have been interviewed. 4- The clothing store are divided into groups (ladies’ store, men’s stores and children’s stores), then the researcher selected sample from each group.

(1-4) Observational and Experimental Studies

Types of studies Observational Studies Experimental Studies

 Observational Study : The researcher merely observes what is happening or what has happened in the past and tries to draw conclusions based on these observations. EX: ” if a researcher records how many students are wearing the Abaya in the Science building over a period of time “  Experimental Studies : the researcher manipulates ( يعالج ) one of the variables and tries to determine how the manipulation influences ( يؤثر ) other variables. EX: patients were randomly assigned into 2 groups. The first one was given drug A and other was given drug B to determine if the drug has an effect patient’s blood pressure.

* “ if researcher counts the numbers of people living in each house in specific time”. What type of study is this? a)Independent study b)Experimental study c)Observational study d)Quasi-experimental study.

** In a true experimental study, the subjects should be assigned to groups randomly. If this is not possible and a researcher uses intact groups, then he is performing a quasi-experimental study.

Every experiment has 2 types of variables The Independent variable explanatory variable The Independent variable or explanatory variable is the one that is being manipulated by the researcher. EX: *Drug *method of study The dependent variable or outcome variable is the resultant variable. EX: *Blood pressure. *Level of sugar in blood *Grade Statistical studies usually include one or more independent variables and one dependent variable.

In the relationship between the number of studying hours and an exam grade, **The number of studying hours is assumed to be ……. a) Nominal variable. b) Independent variable. c) Dependent variable. d) Ordinal variable. **The grade is assumed to be ……. a) Nominal variable. b) Independent variable. c) Dependent variable. d) Ordinal variable.

Suppose that a researcher wants to know if a new teaching method in stat 110 is more effective than an old method in the same course. The researcher divides the students into 2-group randomly, and uses a different method with each group. At the end of the semester, the mean of grades for each group are compared. ** “ Teaching methods” is a (an) ………… variable: a) Dependent b) Independent c) Treatment d) Control ** “ Grade” is a (an) ………… variable: a) Dependent b) Independent c) Treatment d) Control

In the sit up study, there are two group : 1- Treatment group : was a group that received the special instruction. 2- Control group : didn't receive the special instruction.

confounding ( مختلط ) variable is the variable that influences ( interferes ) the dependent or outcome variable but was not be separated from the independent variable. For Example : subjects on exercise program may improve their diet unbeknownst to the researcher and perhaps that improve their health in other ways not due to exercise alone. Then diet becomes a confounding variable.

*The group that received the special instruction in the experimental study is called …………. a) Dependent group b) Independent group c) Treatment group d) Control group *The variable that interferes with other variables in a study is called …………... a) Independent variable b) Confounding variable c) Outcome variable d) Interfering variable

1-5: U SES AND M ISUSES OF STATISTICS 1- Suspect sample : -small samples -convenience sample - volunteer sample For example :” if 4 doctors were surveyed from 100 doctors”.

2- Ambiguous Averages: measures that are loosely called averages are the mean, median, mode and midrange. People who know this can without lying, select one of them to support their position.

3- changing Subject : can occur when different values are used to represent the same data. For example: if one political candidate say “ I will increase salaries a mere 3%” And another one say “I will increase salaries a whapping 6,000,000 $” And 3% =6,000,000

4-Detached Statistic : it is the one in which no comparison is made. For example, one may say that “Our cookies has one-third fewer calories” Here, fewer than what?

5-Implied connection : Usage of words such as may, suggest or some that imply connections but there is no guarantee For example: ” Eating fish may help to reduce your cholesterol”. “studies suggest that using our machine will reduce your weight” “ Taking calcium will lower blood pressure in some people”

6-Misleading Graphs : if graphs are drawn inappropriately, they can misrepresent the data and lead to false conclusions.

7- Faulty Survey Question : should be sure that the questions are properly written since the way questions are phrased can influence the way people answer them. For example: Do u feel that our Alsharafia buildings should build a gum ?

* An advertisement for a new brand of yogurt states, “Almarai yogurt has less calories”, this is an example of: a) Detached Statistics. b) Suspect Sample * “ Eating an apple daily may keep the doctor away” is an example of: a) Detached Statistics. b) Implied connections * “ If only 5 doctors were asked their opinion of new medicine”, this is an example of: a) Detached Statistics. b) Suspect Sample.

If the graph is following: This is an example of: a) Bar chart graph. b) Misleading graph

S UMMARY OF C HAPTER 1 Basic statistics definitions. Descriptive and Inferential Statistics Variables and Types of Data(Qualitative and Quantitative “D &C”). Measurement Scale of Qualitative (Nominal and Ordinal ) Measurement Scale of Quantitative (interval and Ratio) Data collection and sampling techniques. Observational and Experimental Studies Independent and dependent variable Confounding variable. Uses and Misuses of Statistics