A Variable & An Operational Definition : The Nursing

Research Perspective

Titin Andri Wihastuti

Department of NursingMedical Faculty Brawijaya

University

Class Objectives :

After completing this class, the student should be able to :• Exlpain about the variable of nursing research

• Explain about the operational definition of variable

Introduction• An important part of critiquing research is determining whether the author is clear and consistent regarding :–How the concepts in the framework are used in the design of the study

–How the concepts are operationalized into variables

Introduction

Quantitative studies

• “Variables”

Qualitative studies

• “Topics”• “phenomena”

Terms used to refer to the concepts that are being investigated :

Introduction• We are always thinking in “constructs, concepts and variables“……….. It helps us organize and order the world around us.– We think of animals, then fish, then shark.

– This represents :•a construct (animals)•a concept (fish)•a variable (shark)

Constructs, Concepts, Variables

• Construct : a concepts with a general meaning within a conceptual framework (e.g. : emotional responses)

• Concept : term that abstractly describes and names an object or phenomenon (e.g. : anxiety)

• Variable : precise, well-defined concepts that will be measured in research study (e.g. : response to questionnaire anxiety levels)

Constructs• A mental image of a phenomenon• An idea or construct in the mind about thing or an action– a cluster of characteristics that describes the concept

• A construct is broader and more abstract than a concept–construct : quality of life–concepts : satisfaction with self, happiness

Concepts• Range from being very abstract to being very concrete–abstract : anxiety–concrete : body temperature

• Concepts are at a higher level of abstraction than a variable–concept : dyspnea –variable : self-report of dyspnea, respiratory rate

Variables

• A variable is a characteristic, a trait, property, or a condition

• A variable is a characteristic being measured that varies among the persons, places, or objects being studied.

• “variables” are measurable characteristics that can take on different values

Examples :Construct Concept Variable

Symptom distress

Pain

Vomiting

Response to questionanaire behavioral cues

Amount of vomiting

Examples :Construct Concept Variable

Cardiovascular Health

Hypertension

Hypercholesterol emeia

Blood pressure

Lipid levels

Tipe Variabel

1. Berdasarkan jumlah :– Variabel monovariat – Variabel bivariat– Variabel polivariat

• Bagaimana pengaruh pelaksanaan standar praktek keperawatan dengan insidensi komplikasi, penurunan masa rawat inap, penghematan biaya ?

2. Sifat hubungan– Variabel dependent– Variabel independent– Variabel intervening– Variabel extraneous

• Adakah pengaruh terapi kompres hangat dengan penurunan suhu tubuh pasien typoid ?

• Is there a correlation between the number of stress reported by nurses in an intensive care unit and nurses’ desire to leave employment )?

Hubungan antara usia dengan kecelakaan kerja

• Dapatkah penggunaan alat pelindung yang berbeda-beda menjelaskan antara huubungan usia dengan kecelakaan kerja ? (intervening variable)

• Apakah pengaruh jenis-jenis pekerjaan ? (confounding variable)

• Apakah pekerja lansia cenderung mengalami kecelakaan kerja pada tahun-tahun pertama ? (modifier variable)

Pembagian vairabel berdasarkan sifat hubungan penting untuk :

• Menggambarkan kerangka konsep• Mengembangkan kerangka analisis

Variabel dipilih atas dasar relevansinya dengan pertanyaan penelitian, tujuan penelitian dan hypotesis penelitian

Type Variabel

3. Skala pengukuran variabel

• Variabel nominal • Variabel ordinal

• Vatiabel interval• Variabel rasio

Variabel

Kategorikal / Kualitatif

Variabel Kontinyu / Kuantitatif

Categorical variables• Categorical variables are those that are made to fit into a few discrete categories:– Age could be specified as a categorical variable, e.g., 1=young (<30 y.o.); 2=old (>31 y.o.).

– Smoking habit could be specified as a categorical variable, e.g., 1=non smoker; 2=smoker.

Continuous variables • Continuous variables are those that are specified as a range of values along a continuum:– Age could be specified as a continuous variable, e.g., any year of life ranging over the life of the subject.

– Smoking habit could be specified as a continuous variable, e.g., pkgs/day x 365 x #yrs

Nominal• Lowest of the four levels of measurement

• Categories that are not more or less but are different from one another in some way

• Mutually exclusive & exhaustive categories

• E.g. : gender, ethnic background

Ordinal• Categories must be exclusive and exhaustive

• Quantity of the attribute can be identified.

• It cannot be demonstrated that the intervals are equal: unequal intervals

Ordinal• Many scales in nursing research are ordinal scales

• Some may be referred to as metric ordinal scales are are treated as interval scales if the intervals are considered to have some evenness.

•How often do you feel in control of your life?•(1) Never•(2) Seldom•(3) Often•(4) Almost always

Rating Scale

SCALING• Rating Scales--ordered series of categories of a variable based on an underlying continuum.– Never, Sometimes, Often, Frequently

• Likert Scale– Strongly agree, agree, neutral, disagree, strongly disagree

INTERVAL SCALE•In this case, the distance between these ordered category values are equal because there is some accepted physical unit of measurement. In the Fahrenheit thermometer, mercury rises in equal intervals called degrees.

INTERVAL SCALE CONT..•However, the zero point is arbitrary, chosen because Daniel Fahrenheit, the inventor, decided that zero point on this scale would be 32 degree below the freezing point of water.

INTERVAL SCALE CONT..•Because the units are in equal intervals, it is possible to add and subtract across an interval scale.

•You can say that 1000 F is warmer than 500, but you cannot say that 1000 F is twice as hot as 500 F.

• Highest for measurement• Continuum of values • Absolute zero point• Weight, height, volume

Ratio

• Pembagian variabel berdasarkan skala pengukurannya dikembangkan sebagai bahan pertimbangan dalam mengkaji status metode analisis data

• Setiap skala variabel yang berbeda mempunyai konsekuensi sifat analisis teknik analisis yang berbeda.

Latihan :1.Status ISPA2.Suhu Badan3.Cakupan imunisasi4.Tingkat pendidikan5.Prevalensi TB Paru 6.BOR

7. LOS8. Jenis Malaria

9. Biaya pelayanan kesehatan

10. Status imunisasi

11. Status gizi

Latihan :12. Status sosial ekonomi13. Persepsi terhadap

DHF14. Status ANC15. Kadar HB16. Jenis Hepatitis17. Morbiditas penyakit

diare

18.Cara pembayaran pelayanan kesehatan

19.Paritas20.Jumlah

peneriamaan tablet besi

21.Pengetahuan ibu tentang larutan gula garam

Operationalizing Research Variables

•Conceptual Definition:•The abstract meaning of a variable that usually is based on theory.

•Operational Definition:•A way of defining a variable that makes it measurable or manipulatable in the real world.

An “operational definition”

• An operational definition is how the researcher defines the variable in measurable terms.– Given the mechanical means thus far invented to operationalize the concept of diastolic blood pressure, different methods may necessarily distort the definition, and the results:• Will dBP be defined by auscultation as the 4th or 5th Korotkoff sound?, or

• Will dBP be defined by the nadir of the direct arterial pressure wave’s dicrotic notch?, or

• Will dBP be defined by the arterial pressure at which ECG indicates peak ventricular electrical repolarization?

An “operational definition”• Heart rate is a concept defined in intellectual terms as the

frequency that cardiac contractile cycles are recurring one after another.

• Researchers can come up with different ways to measure heart rate, among which some ways are more sophisticated than others :– Palpation of a peripheral arterial pulse [feel]– Auscultation or Doppler [listen]– Visual by echocardiographic observation [look]– ECG [indirect]– Photomagnetic oscillations [indirect]

• the operational definition of heart rate would have to be modified if it was important to account for observations in which the number of atrial and ventricular contractile cycles per unit of time did not correspond.

An “operational definition”

• Is there such a thing as love?, or happiness? [love and happiness are concepts that virtually everyone can identify, but can’t agree on how to measure]

• Can the degree to which people love other people change?, and does people’s happiness vary and function as the cause or result of circumstances? [if yes, then they are variables]

• If you want to study them quantitatively, you will have to operationalize love and happiness in measurable terms. Any ideas for how to go about doing that?

Cara mengoperasionalisasikan variabel :

• Hindari istilah dalam kamus / tekstual• Mendefinisikan dalam makna kontekstual

• Hindari pernyataan dalam bentuk negatif

• Apa yang didefinisikan tidak boleh masuk dalam definisi

• Tidak dinyatakan dalam bahasa yang kabur (ambigous)

Alasan Mendefinisikan Variabel Penelitian

1. Agar tidak menimbulkan kekaburan fokus penelitian dan menghilangkan salah penafsiran terhadap obyek yang menjadi fokus penelitian

2. Mempersempit fokus target populasi dan wilayah penelitian

3. Memudahkan pembuatan instrumen penelitian

4. Memberi makna kontekstual terhadap masalah yang menjadi fokus

SummaryConstruct

Concept

Variables

Operational Definition

Indicators

Measurement

Suggested ReadingsDanim, S. 1997. Metode Penelitian untuk Ilmu-

ilmu Perilaku. Jakarta : Binarupa Aksara

Nursalam. 2003. Konsep dan Penerapan Metodologi Penelitian Ilmu Keperawatan : Pedoman Skripsi, Tesis dan Instrumen Penelitian Keperawatan. Jakarta : Penerbit Salemba Medika. Hal : 100 – 1065.

Polit, D. F. Hungler, B. P. 1999. Nursing Research : Principles and Metods. 6th ed. Philadelphia : J. B. Lipincott.

Tim Metodologi Fakultas Kedokteran. 2003. Dasar-dasar Metode Penelitian Keperawatan. Buku Diktat PSIK FK Unbraw. Tidak diterbitkan. Malang