Variables
Qualitative variables
Qualitative variables are variables that can be placed into distinct categories, according to some characteristic or attribute.For example, gender (male or female).
- Kategorial (categorical) variable
- Contoh: jenis kelamin, warna, dll
Quantitative variables
Quantitative variables are numerical in nature and can be ordered or ranked.Example: age is numerical and the values can be ranked.
- Numerical variable
- Contoh: umur, berat badan, dll
Discerete variables
Discrete variables assume values that can be counted.
- Hanya dapat mengambil nilai tertentu
- Contoh: jumlah anak, jumlah kamar, dll
Continuous variables
Continuous variables can assume all values between any two specific values. They are obtained by measuring.
- Dapat mengambil nilai apapun dalam suatu rentang
- Contoh: berat badan, tinggi badan, dll
Data Types
Nominal level of measurement
Thenominal level of measurement classifies data into mutually exclusive (nonoverlapping), exhausting categories in which no order or ranking can be imposed on the data.
- Kategori tanpa urutan
- Contoh: jenis kelamin, warna, dll
Ordinal level of measurement
Theordinal level of measurement classifies data into categories that can be ranked; precise differences between the ranks do not exist.
- Urutan dan tidak terstruktur
- Contoh: tingkat pendidikan, kelas sosial, dll
Interval level of measurement
Theinterval level of measurement ranks data; precise differences between units of measure do exist; there is no meaningful zero.
- Urutan dan memiliki jarak antar nilai yg sama (interval)
- Contoh: suhu, IQ, dll
- Skor 176-225: teramat sangat berbakat (profoundly gifted)
- Skor 161-175: sangat berbakat (extremely gifted)
- Skor 130-144: berbakat (gifted)
- Skor 120-129: superior
- Skor 110-119: di atas rata-rata (high average)
- Skor 90-109 : rata-rata (average)
- Skor 80-89 : di bawah rata-rata (low average)
- Skor 70-79 : batas tertinggal (borderline delayed)
- Skor 55-69 : sedikit tertinggal (midly impaired)
- Skor 40-54 : cukup tertinggal (modearately delayed)
Ratio level of measurement
Theratio level of measurement possesses all the characteristics of interval measurement, and there exists a true zero. In addition, true ratios exist for the same variable.
- Urutan, memiliki jarak antar nilai yg sama, dan memiliki nilai 0 yg bermakna “tidak ada”.
- Contoh: berat badan, tinggi badan, dll
References
Contoh Soal Variables
Classify each variable as qualitative, quantitative, discrete or continuous.1
Qualitative
- Colors of baseball caps in a store.
- Classification of children in a day care center (infant, toddler, preschool).
- Marital status of faculty members in a large university.
2
Quantitative
- Number of bicyles sold in 1 year by a large sporting goods store.
- Times it takes to cut a lawn.
- Capacity in cubic feet of six truck beds.
- Weights of fish caught in Lake George.
3
Discrete
- Number of doughnuts sold each day by Doughnut Heaven.
- Lifetime (in hours) of 12 flashlight batteries.
- Number of Cheeseburgers sold each day by a hamburger stand on a college campus.
- Number of DVDs rented each day by a video store.
- Capacity (int gallons) of six reservoirs in Jefferson County.
4
Continuous
- Water Temperatures of six swimming pools in Pittsburgh on a given day.
- Weights of cats in a pet shelter.
Contoh Soal Data Types
Classify each as nominal-level, ordinal-level, interval-level, or ratio-level measurement.1
nominal-level
- Marital status of patients in a physician’s office.
2
ordinal-level
- Rankings of tennis players.
- Ratings of eight local plays (poor, fair, good, excellent).
3
interval-level
- Temperatures inside 10 refrigerators.
4
ratio-level
- Pages in the city of Cleveland telephone book.
- Weights of air conditioners.
- Salaries of the top five CEOs in the United States.
- Times required for mechanics to do a tune-up.
- Ages of students in a classroom.
- Horsepower of tractor engines.
Contoh Soal
Safe Travel Read the following information about the transportation industry and answer the questions. transportation Safety The chart shows the number of job-related injuries for each of the transportation industries for 1998.| Industry | Number of injuries |
|---|---|
| Railroad | 4520 |
| Intercity bus | 5100 |
| Subway | 6850 |
| Trucking | 7144 |
| Airline | 9950 |
- What are the variables under study?
Answer:Industry and number of injuries. - Categorize each variable as quantitative or qualitative.
Answer:Industry is qualitative and number of injuries is quantitative. - Categorize each quantitative variable as discrete or continuous.
Answer:Number of injuries is discrete. - Identify the level of measurement for each variable.
Answer:Industry is nominal and number of injuries is ratio. - The railroad is shown as the safest transportation industry. Does that mean railroads have fewer accidents than the other industries? Explain.
Answer:No, the number of injuries is not the same as the number of accidents. The number of injuries is the number of people who were injured in job-related accidents. The number of accidents would be the number of accidents that occurred. The number of injuries is not the same as the number of accidents. The number of injuries is the number of people who were injured in job-related accidents. The number of accidents would be the number of accidents that occurred. - What factors other than safety influence a person’s choice of transportation?
Answer:Cost, convenience, time, comfort, and personal preference are factors that influence a person’s choice of transportation. - From the information given, comment on the relationship between the variables.
Answer:The number of injuries is related to the industry. The number of injuries is the dependent variable, and the industry is the independent variable. The number of injuries is related to the industry. The number of injuries is the dependent variable, and the industry is the independent variable.