A. The Definition Of Statistic• Statistics is a study or scientific method of collecting, organizing, processing, presenting, analizyng data and drawing a conclusion according to the result of the data analysis.
1) Presenting Data From the following definition, we know that statistics is closely releated to data.• Data is the information obtained from the result of observation or research .• The singular form of data is datum• Data can describe a situation, so that based on the data we can draw a conclution
According to the types, data can be divided into two. They are :1. Qualitative data are data releated to the category or characteristic of an object. For examples : a. Data about the cleanest country in the world (Singapore, Japan, Australia, or the other) b. Data about the best female singer (BoA, Taylor Swift, Beyonce, Rihanna, Whitney Housten or the other)Qualitative data are usually obtained by interview
2. Quantitative data, are obtained from the result of numerical recording (in the form of numbers) For examples are : a. Data about the weight in the class (48kg, 45.5kg, 45kg, 49kg, 48kg, 50kg and so on) b. Data about the number of sister (2, 3, 2, 4, 1, 0 and so on)
As we know, the data are used to draw aconclusion. But before draw a conclusion, thedata that have been collected beforehandarranged, processed, presented, then analyzedcarefully, accurately and according to the right theory.Based on the data that have been analyzed, wecan draw a conclusionThere are several examples of conclutions :a. The average of students in the class IX E is 14 years oldb. The favorite teacher in Nedusi is Mr. Yokoc. The favorite subject in class IX E is Mathematic
2). Collection of Data• Collection of data is the beginning stage (the first step) in the statistical activity.• Collecting data can be performed by interview of questionnaire, then continued by one of the following activities : a. Counting b. Measuring c. Recording data by tallies
3). Ordering Single Data• Simple data is only consist of relatively small data.• It isn’t necessary to group them, ordering data is enaugh• In general, the collected statiscal data are still scattered and the measurement isn’t in order.• However, to simply presentation and processing of data, we need to order them from the lowest value to the highest value. After the data are ordered, we can determine the highest and the lowest value of data.
Measures Of Central Tendency• The collected and even the ordered data don’t automatically give clear information.• To get clearer information, we need measures to represent the collection of data.• The measures are known as the measures of central tendency• By knowing measures of central tendency, we can find out the value of the centralized data.
The Measures Of CentralTendency Consist Of 3 Measures, Namely :1. MEAN (arithmetic mean)2. MODE (the value that occurs most often)3. MEDIAN (the middle value)
1. Mean• In statistic, the average value is usually called arithmetic mean or simply mean.• So, mean is the average value of all data values• Mean is one of the measures of central tendency that is most often used.• The mean of data set is the sum of all data values divided by the number of data. X ☞ X nExample : Data = 7 8 9 8 5 9 9 6 4 The ordered data =4 5 6 7 8 8 9 9 9 = 7.3
2. Mode • Mode is generally used to express the tendency which most frequently happens. • In statistics, the mode means the value that occurs most frequently or the value of highest frequency. Example : Data = 3 5 8 6 5 9 8 8 6 No. Marks Tally FrequencyThe ordered data = 3 5 5 6 6 8 8 8 8 9 1. 3 l 1 2. 5 ll 2 3. 6 ll 2 Based on the data above, the 4. 8 llll 4 value of highest frequency is 5. 9 l 1 8 So, the mode is 8
3. Median • Median is a measure of central tendency used to analyze data. • If the number of data ordered is odd, then the median is the data value right in the middle that divides the data into two equal parts • And if the number of data ordered is even, then the median is the mean of two data values in the middle Median = The middle value after being ordered Example :a. If n is odd, then the median is Data : 9 9 7 5 8 7 3 6 4 The ordered data : 3 4 5 6 7 7 8 9 9 Because n is odd (9), so the median is in the order to :b. If n is even, then the median is 5 Median = 3 4 5 6 7 7 8 9 9 4 Median 4 So, the median is 7
C. The Presentation Of Data• The data collected and ordered according to the need should be presented in a certain form in such away that they can be read and interpreted easilyThe presentation of statiscal data can be performed in twomethods, they are : 1. Presented in the form of list or table a. Frequency table of single data b. Frequency table of grouped data 2. Presented in the form of a diagram or graph a. Pictogram (A method of presenting information using picture) b. Bar chart (A method of presenting data in bars) c. Line graph (A method of presenting data in a line) d. Pie charts (A method of presenting data in a circular region)
Quartile• Quartile means the grouping of four, split the data that has been sorted into four equal parts.• To present quartile, we used Q symbol.Q₁ = initial quartile / bottom quartile (¼)Q₂ = middle quartile / median (¾)Q₃ = upper quartile (²⁄₄)
We Have SomeObservation In ClassVII C And Class VII G Curious ? Do you want to know ? Serious ?Okay Let’s check it out !
Observation In Class VII G (Quantitative Data) Questions :1. How many sister do you have?2. How many brother do you have?3. When you were in class six, what rank did you get ?
1. The Number of Sisters Owned by Students of VII G Sisters 12 10 Havent SisterStudents 8 Have 1 Sister 6 Have 2 Sisters 4 Have 3 Sisters 2 Have 4 Sisters 0 Have 5 Sisters Havent Have 1 Have 2 Have 3 Have 4 Have 5 Sister Sister Sisters Sisters Sisters Sisters
So, from the data we can make a conclution : a. The students that haven’t sister are 10 students b. The students that have 1 sister are 8 students c. The students that have 2 sisters are 6 students d. The students that have 3 sisters are 2 students e. The student that have 4 sisters is nothing f. The students that have 5 sisters are 2 studentsThe number of students that have the most sister are 2 studentsAnd the students that haven’t sister are 4 students
2. The Number of Brothers Owned by Students of VII G Broters Students That Havent 6 Brother 10 Students That Have 1 Brother 3 Students That Have 2 Brothers Students That Have 3 9 Brothers
So, from the data we can make the conclution : a. The students that haven’t brother 10 students b. The students that have 1 brother are 9 students c. The students that have 2 brothers are 3 students d. The students that have 3 brothers are 6 students e. The student that have 4 brothers and 5 brothers is nothingThe number of students that have the most brothers (3 brothers) are6 studentsAnd the number of students that haven’t brother are 10 students
3. The Rank Of Ranked StudentsStudents VII G 1 2 When They 3 4 Were In Class 5 Six 8 9 10 11 12 13 14 18 19 20
4. The Interest or The Favorite Language in Grade VII C Favorite LanguageBahasa Indramayu France Bahasa Indonesia English Japan Japan English France Bahasa Indramayu Bahasa Indonesia 0 2 4 6 8 10 12 14
Observation In Class VII C (Qualitative Data)Question :1. What kind of language do you like ?2. Which country will be visited most ?3. Which city will you go to your study tour ?
So, From The Data We Can Make Conclution :a. The students who interested in Bahasa Indonesia are 3 studentsb. The students who interested in English are 14 studentsc. The students who interested in Japan Language are 9 studentsd. The students who interested in France are 2 studentse. The student who interested in Indramayu Language is nothingSo, English is the most interestedlanguage. And Indramayu language isn’tinterested with all students VII C
5. The Country Will Be Visited Most By Students VII C The Countries 4% 4% 3% 7% South Korea 41% 24% Japan 17% France Saudi Arabia Holand Rumania The number of students VII C is 28 Australia students
So, from the data we can make the conclution :o The number of students VII C will be visited South Korea are 12 studentso The number of students VII C will be visited Japan are 5 studentso The number of students VII C will be visited France are 7 studentso The number of students VII C will be visited Saudi Arabia are 2 studentso The number of students VII C will be visited Holand is 1 studento The number of students VII C will be visited Rumania is 1 studento The number of students VII C will be visited Australia is 1 student So, the city will be visited most is South Korea And the city will be visited least is Holland, Rumania, and Australia
6. The City That Very Want To Visit To Your Study tour 12 10 Bali 8 Lombok YogyakartaFrequency 6 Paris 4 Jakarta 2 Bandung Raja Ampat 0 0 2 4 6 8 -2
So, from the data we can make the conclusion• The students who choose Bali to visit to their study tour are 11 students• The students who choose Lombok to visit to their study tour are 5 students• The students who choose Yogyakarta to visit to their study tour are 2 students• The students who choose Paris to visit to their study tour are 5 students• The student who choose Jakarta to visit to their study tour is nothing• The student who choose Bandung to visit to their study tour is nothing• The student who choose Rajaampat to visit to their study tour is 1 student So, the city that most choose to visit to students of VII C’s study tour is South Korea And the cities that not choose to visit to students of VII C’s study tour are Jakarta and Bandung
We Have Learnt About StatisticsSo, let’S try to anSwer these exercises
EXERCISE1. Given the following data 2681435394 6842552555 4877694675 Based on the data above : a. Make the frequency table b. Find the mean, the mode and the median
2. The mean mark of mathematics test of 15 students is 8.6 if Sofhie’s mark is included, then the mean mark becomes 8.7 find Dinda’s mark in the test.3. The mean weight of agroup of children is 38 kg.Children having a meanweight of 40 kg areadded, then the meanweight becomes 38.4 kg.Find the number ofchildren at first
4. Consider the table below KINDS OF PEOPLE’S OCCUPATIONS IN VILLAGE A NO. Kinds Of Occupations Frequency 1 Public Servants 56 2 Private Employees 42 3 Farmers 84 4 Traders 126 5 Workers 28The frequency table above shows the data about thekinds of occupations of people at a village. Make a piechart based on the data.
5. The number of classes and the class interval in the table of frequency distribution respectively are ... Value Frequency 30-34 2 35-39 7 40-44 11 45-49 4 50-54 3