Business Statistics: A Decision-Making Approach 7 th Edition

Transkripsi

1 Business Statistics: A Decision-Making Approach 7 th Edition Chapter 1 The Where, Why, and How of Data Collection Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-1

2 Perangkat pada Statistik Statistik Deskriptif Pengumpulan, penyajian, dan penjelasan data Statistik Inferensial Menggambarkan kesimpulan dan/atau membuat keputusan yang berkaitan dengan populasi berdasarkn hanya pd sample data Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-2

3 Statistik Deskriptif Pengumpulan data e.g., Survey, Observasi, Eksperimen Penyajian data e.g., Chart and grafik Pengkarakteristikan data e.g., Rata2 sample = n x i Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-3

4 Statistik Inferensial Membuat pernyataan tentang populasi dengan memeriksa hasil dari sample Sample statistics (diketahui) Parameter population Inferensi (tdk diketahui, tetapi dapat diestimasi dr bukti sample) Sample Population Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-4

5 Statistik Inferensial Menggambarkan kesimpulan dan/atau membuat keputusan berdasarkan populasi berbasis pd hasil sample. Estimasi e.g., Estimasi rerata bobot populasi menggunakan rerata bobot sample Pengujian Hipotesis e.g., Menggunakan bukti sample utk menguji penyataan bahwa rerata bobot populasi adalah 120 pounds Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-5

6 Perangkat Pengumpulan Data Metode Pengumpulan Data Eksperimen Survey Telepon Menulis kuestioner Observasi langsung dan wawancara personal Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-6

7 Langkah-langkah Disain Survey Mendefinisikan isu Apa maksud dan tujuan dari survey? Mendefinisikan populasi yang dibutuhkan Mengembangkan pertanyaan survey Membuat pertanyaan yang jelas dan tdk ambigu Menggunakan definisi yang umum dan dapat diterima Membatasi jumlah pertanyaan Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-7

8 Langkah-langkah Disain Survey Tes awal survey Percobaan awal dengan jumlah sedikit partisipan mengasess kejelasan dan rentangnya Menentukan ukuran sample dan metode sampling (continued) Memilih sample dan mengelola hasil survey Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-8

9 Tipe2 Pertanyaan Pertanyaan Tertutup Memilih short list definisi pilihan Ex: Major: business liberal arts science other Pertanyaan Terbuka Responden bebes memberikan to respond dengan nilai, katakata, atau statement Ex: Apa baiknya dari kursus ini? Pertanyaan Demograpi Pertanyaan tentang karakteristik personal responden Ex: Gender: Female Male Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-9

10 Populasi dan Sample Populasi adalah sekumpulan semua items or individual yang berkaitan Examples: Semua pemilik kendaraan Semua spare part yang diproduksi Semua sales receipts bulan November Sample adalah subset dari populasi Examples: 1000 pmilik kendaran yg dipilih secara acak sebagian parts yg diambil melaui teori peluang setiap 100 th receipt dipilih utk audit Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-10

11 Definisi Kunci population adalah Suatu parameter adalah ukuran yg dihitung untuk menjelaskan karakteristik suatu populasi sample adalah sebagian dari populasi yang dipilih untuk dianalisis statistic adalah ukuran summary untuk menjelaskan karakteristik dari sample Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-11

12 Populasi vs. Sample Populasi a b c d ef gh i jk l m n o p q rs t u v w x y z Sample b c g i n o r u y Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-12

13 Mengapa Sample? Less time consuming than a census Less costly to administer than a census It is possible to obtain statistical results of a sufficiently high precision based on samples. Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-13

14 Sampling Techniques Sampling Techniques Nonstatistical Sampling Convenience Judgment Simple Random Statistical Sampling Stratified Systematic Cluster Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-14

15 Statistical Sampling Items of the sample are chosen based on known or calculable probabilities Statistical Sampling (Probability Sampling) Simple Random Stratified Systematic Cluster Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-15

16 Simple Random Sampling Setiap sampel yang mungkin memiliki kesempatan yang sama untuk dipilih Pemilihan mungkin dengan pengembalian atau tanpa pengembalian Sample dapat diperoleh menggunakan suatu table bilangan acak atau computer random number generator Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-16

17 Stratified Random Sampling Divide population into subgroups (called strata) according to some common characteristic Select a simple random sample from each subgroup Combine samples from subgroups into one Population Divided into 4 strata Sample Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-17

18 Systematic Random Sampling Decide on sample size: n Divide frame of N individuals into groups of k individuals: k=n/n Randomly select one individual from the 1 st group Select every k th individual thereafter N = 64 n = 8 k = 8 First Group Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-18

19 Cluster Sampling Divide population into several clusters, each representative of the population Select a simple random sample of clusters All items in the selected clusters can be used, or items can be chosen from a cluster using another probability sampling technique Population divided into 16 clusters. Randomly selected clusters for sample Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-19

20 Data Types Data Qualitative (Categorical) Quantitative (Numerical) Examples: Marital Status Political Party Eye Color (Defined categories) Examples: Discrete Number of Children Defects per hour (Counted items) Continuous Examples: Weight Voltage (Measured characteristics) Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-20

21 Data Types Time Series Data Ordered data values observed over time Cross Section Data Data values observed at a fixed point in time Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-21

22 Data Types Sales (in $1000 s) Atlanta Boston Cleveland Denver Time Series Data Cross Section Data Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-22

23 Data Measurement Levels Measurements Ratio/Interval Data Highest Level Complete Analysis Rankings Ordered Categories Ordinal Data Higher Level Mid-level Analysis Categorical Codes ID Numbers Category Names Nominal Data Lowest Level Basic Analysis Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc.

24 Chapter Summary Reviewed key data collection methods Introduced key definitions: Population vs. Sample Qualitative vs. Quanitative data Primary vs. Secondary data types Time Series vs. Cross-Sectional data Examined descriptive vs. inferential statistics Described different sampling techniques Reviewed data types and measurement levels Business Statistics: A Decision-Making Approach, 7e 2008 Prentice-Hall, Inc. Chap 1-24