# Stat 110 Kau Homework

## Presentation on theme: "G ENERAL S TATISTICS S TAT 110. C OURSE I NFORMATION : Course name and number : General Statistics. STAT 110 Course website address: kau.edu.sa/Pages-stat-110-"— Presentation transcript:

1 G ENERAL S TATISTICS S TAT 110

2 C OURSE I NFORMATION : Course name and number : General Statistics. STAT 110 Course website address: http://stat. kau.edu.sa/Pages-stat-110- female-section.aspx

3 Textbook : Elementary Statistics a Step by Step Approach, 9th Edition by Allan Bluman, McGraw/Hill, 2009.

4 :COURSE SYLLABUS Chapter 1: The Nature of Probability and Statistics Chapter 2: Frequency Distributions and Graphs Chapter 3: Data Description Chapter 4: Probability and Counting Rules Chapter 5: Discrete Probability Distributions Chapter 6: The Normal Distribution Chapter 10: Correlation and Regression + Chapter 13

5 CHAPTER 1 The Nature of Probability and Statistics

6 S TATISTICS is the science of conducting studies to collect, organize, summarize, analyze and drawing conclusions from data.

7 I NTRODUCTION A Variable A Variable: is characteristic or attribute that can assume different values. Data: Data: are the values (measurements or observations) that the variables can assume. Random Variable : Random Variable : variables whose determined by chance. Data set Data set : Collection of data values. Datum Or a data value Datum Or a data value Each value in the data set

8 A population: consists of all subjects (human or otherwise) that are being studied. A sample : is a subset of the population (i s a group of subjects selected from a population) For example : In order to study the response times for emergency 988 calls in Jeddah 50 calls are selected randomly over a six month period and the response times are recorded. Population : all calls 988. Sample : 50 calls.

9 genderage male 20 male 25 female 30 male 23 female 30 B A c D Nationality Saudi Yemeni Egypt Jordanian Lebanese ( Variable, Data Set, Data value, Data)

10 Branches of Statistics Descriptive statistic Inferential statistic consists of the collection, organization, summarization, and presentation of data. For example : -the average age of the student is 14 years. -the median household income for people aged 25-34 is 35.888$. consists of generalizing from samples to populations, performing estimations and hypothesis tests, determining relationships among variables, and making predictions. For example: the relationship between smoking and lung cancer. probability.

11 Determine whether Descriptive or Inferential statistics were used: a. The average jackpot for the top five lottery winners was $367.6 million. b. A study done by the American Academy of Neurology suggests that older people who had a high caloric diet more than doubled their risk of memory loss. c. In 2011,79% of U.S. adults used the Internet. d. In 2011,there were 34 deaths from the avian flu. Descriptive Inferential Descriptive

12 E XAMPLE : A researcher asked 80 students at KAU about their weight. As a result of this information, the average weight of students at KAU was 59kg. Which branch of statistics was used in this survey? Observational Experimental Inferential Descriptive

13 E XAMPLE : "There is a relationship between IQ tests and the final score student" Which branch of statistics is Observational Experimental Inferential Descriptive

14 1-2:V ARIABLES AND T YPES OF D ATA variables QualitativeQuantitative DiscreteContinuous

15 Types of Variables ( Classify ) Types of Variables ( Classify ) Qualitative Variables: Quantitative variables are variables that have distinct categories, according to some characteristic or attribute. For example: Gender, Color……etc are numerical and can be ordered or ranked. are variables that can be counted or measured. For example: Age,Height, Weight,temperature …..etc

16 Discrete Variables Continuous Variables Quantitative variables classified into two groups assume values that can be counted. For example: Number of children in a family, Number of student in classroom, Number of DVDs rented each day ……etc assume an infinite number of values between any two specific values. They are obtained measuring, they often Include fractions and decimals For example: Temperature, Height Weight Time …..etc

17 Measurement Scales Qualitative NominalOrdinal Quantitative Interval Ratio

18 Nominal level Ordinal level: Measurement Scale of Qualitative classifies data into mutually exclusive, (nonover lapping) categories in which no order or ranking can be imposed on the data. For example: Eye color,Gender, Political party, blood types …etc classifies data into categories can be ranked. For example: Grade of course (A,B,C), Size( S,M,L) Rating scale (Poor,Good,Excellent ) Ranking of tennis players …etc

19 Interval level Ratio level ranks data and precise differences between units of measure do exist,however there is no meaningful zero. For example: Temperature, possesses all the characteristics of interval and there exist a true zero. For example: Height, Weight, Time, Salary, Age …etc Measurement Scale of Quantitative

20 E XAMPLE : 1- Blood Type,an example of which type of data? Qualitative Ordinal Continuous Discrete 2- Area of the Kingdom of Saudi Arabia, is an example of which type of data? Discrete Qualitative Nominal Continuous

21 E XAMPLE : Number of stores represents a Quantitative variable Discrete variable Continuous variable Interval variable Classify " Temperature in Jeddah": Interval Qualitative Continuous Discrete

22 E XAMPLE : If you classified the fruit in a basket as apple, orange and banana, this would be an example of which level of measurement? Ordinal Ratio Nominal Interval

23 E XAMPLE Which of the following represents ordinal level of measurement? Rating scale IQ score Age Marital status Which one of the following variables is Qualitative? Amount of fat in a piece of cheese Salary of college professors Favorite TV program Age of a person

24 1-3 Data collection and sampling techniques

25 Data collection Survey Studies Telephone surveys Mailed questionnaire surveys Personal interview

26 Some Sampling techniques Random Sampling Systematic Sampling Stratified Sampling Cluster Sampling

27 1-R ANDOM S AMPLING : A random sample is a sample in which all members of the population have an equal chance of being selected. Are selected by using chance methods or random numbers.

28 F OR EXAMPLE : F OR EXAMPLE : S ELECT RANDOM SAMPLE OF 15 SUBJECTS OUT OF 85 SUBJECTS, EACH SUBJECT NUMBERED FROM 1 TO 85

29 Are obtained by numbering each value in the population and then selecting the kth value. is a sample obtained by selecting every k th member of the population where K is counting number. K =N/n n is the sample size, and N is the population size. 2-S YSTEMATIC S AMPLING

30 Decide on Sample Size: n Divide Frame of N individuals into Groups of k Individuals: k=N/n Randomly Select One Individual from the 1st Group Select Every k th Individual Thereafter N = 64 n = 8 k =64/8= 8 First Group

31 3-S TRATIFIED SAMPLES is a sample obtained by dividing the population into subgroups or (strata ) according to some characteristic relevant to the study. Then subjects are selected from each subgroup. For example : A researcher select a random sample from each gender to check their blood pressure.

32

33 4-C LUSTER SAMPLES is obtained by dividing the population into sections or clusters and then selecting one or more clusters and using all members in the cluster(s) as the members of the sample 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.

34 Randomly selected 2 clusters Population divided into 4 clusters Randomly

35 S UMMARY OF SAMPLING TECHNIQUES Random : random number generator. Systematic :every kth subject. Stratified :divide population into group called “strata”. Cluster :use intact groups. Convenient : a researcher uses subjects that are convenient. Exp.: (a researcher in the mall…..).

36 * E XERCISES : 1- A researcher wanted to do a study about doctor’s income in Jeddah. He divided hospitals into two sectors (private and public) then he took a sample from each sector.

37 * E XERCISES : 2- A researcher wanted to know doctors opinion about herbal therapy in Jeddah. For this study he choose randomly 3 hospitals out of 20 hospitals in Jeddah, and all doctors in the 3 hospital were asked.

38 1- What type of sampling if employees is divided into Education classes and a sample is chosen from each class to be surveyed? 2- Researcher select 10 devices from different labs to be tested, What type of sampling in that example ? 3- Every seventh customer entering a shopping mall is asked to select her or his favorite store. What type of sampling methods has been used in that example ?

39 1-4 Observational and Experimental Studies

40 Types of studies Observational Studies Experimental Studies

41 1-4: O BSERVATIONAL AND E XPERIMENTAL S TUDIES 1- 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. For example :” if a researcher records how many students are wearing the Abaya in the Science building over a period of time “.

42 1-4: O BSERVATIONAL AND E XPERIMENTAL S TUDIES 2- 2- Experimental Studies : the researcher manipulates one of the variables and tries to determine how the manipulation influences other variables. For example : 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.

43 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.

44 1-4: O BSERVATIONAL AND E XPERIMENTAL S TUDIES 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.

45 E XAMPLE : Subject were randomly assigned to two groups, and one group was given drug A and the other group drug B.After 6 months, the mean of blood pressure for each group wear compared. This is an example of what type of study? Outcomes study Independent study Observational study Experimental study

46 E XAMPLE : 1- "If researcher observes and counts the number of cars in parking ". What type of study was this? Independent study Experimental study Observational study Quasi-experimental study

47 Dependent Variable or Outcome Variable Any Experiment has 2 Variables Independent Variable or Explanatory Variable (or input) variable is the one that is being manipulated by the researcher. is the resultant variable

48 1-4: O BSERVATIONAL AND E XPERIMENTAL S TUDIES Statistical studies usually include one or more independent variables and one dependent variable.

49 For example Independenttemperature of water exercise Dependenttime to cook an egg health

50 A confounding variable is the variable that influences the dependent or outcome variable but was not be separated from the independent variable. ( variable that influence with other 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.

51 E XAMPLE : Subject were randomly assigned to two groups, and one group was given drug A and the other group drug B.After 6 months, the mean of blood pressure for each group wear compared. 1-What is the dependent variable in the study? 2-What is the independent variable in the study? 6 month Number of groups Type of drug Blood pressure

52 1-5: U SES AND M ISUSES OF STATISTICS 1- Suspect sample : 2- Ambiguous Averages 3- changing Subject 4-Detached Statistic 5-Implied connection 6-Misleading Graphs Faulty Survey Question

53 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.

54 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?

55 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”

56 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: What is your opinion about WHO Organization

Такой поиск, по существу, представляет собой команду компьютеру просмотреть все строки знаков на жестком диске, сравнить их с данными громадного по объему словаря и пометить те из них, которые кажутся бессмысленными или произвольными. Это сложнейшая работа, заключающаяся в постоянном отсеивании лишнего, но она вполне выполнима. Сьюзан понимала, что, по всей логике, именно ей предстояло решить эту задачу.

Она вздохнула, надеясь, что ей не придется раскаиваться в том, чем она собиралась заняться.

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