measurement data collection
Post on 18-Jul-2015
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measurement principles and Data collection methodsPrepared by
Hoda FawzyManal GharibA beer MohamedNaglaa HamidNaglaa fouzy Under Supervision Prof. Dr./sohair mekhaemar Prof. Dr./ shadia hamido Out lineIntroductionmeasurement principlesLevels of measurement Converted data to a lower level of measurementDetermining The appropriate level of measurementData-collection processData-collection methodsData-collection instrumentCriteria for selection of data collection instrumentvalidity of instrumentCategories of validity1- Face validity 2- Content validity3-Criterion validity4- Construct validity
Relation ship between reliability and validity-Sources of error in data collectionPreparing data for analysisUse of statistical consultantCritiquing the data-collection proceduresGuidelines for critiquing the data-collection procedures
Data collection method :- 1- Questionnaire. 2- Interviews. 3- Observation methods. 4- Physical measures. 5- Attitude scale. 6- Psychological tests. 7- Q sorts. 8- Delphi technique. 9- Visual analogue scale. 10- Preexisting data summary
introductionMany researchers get excited when they talk about the data collection phase of their studies. this when the real detective work begins
An understanding of measurement principles and the data collection process is important for the nurse researcher
measurement principlesMeasurement is the process of assigning numbers to variables it include counting ,ranking, and comparing objects or events
Some qualitative studies gather data in narrative form and numbers are not associated with these data so these data not included in the concept of measurementLevels of measurement
1 - Nominalclassification by name Numbers are obtained for this type of data through counting the frequency or percentages of objects or events in each of the categories .e.g. ( gender, religious affiliation, marital status, and political party membership )
The nominal level of measurement is considered the lowest level of the measurement levels2 - Ordinal Numbers are obtained form this measurement process indicate the order rather than the exact quantity of variableFor example, anxiety levels of people in a therapy group might be categorized as mild, moderate, and severe.
3 - Interval Data not only can be placed in categories and ranked but also the distance between the ranks can be specified
The categories in Interval data are the actual numbers on the scale (such as on a thermometer)4. Ratio Data collected at the ratio level of measurement are considered the 'highest' level of data. Ratio level of measurement includes data that can be categorized and ranked; in addition, the distance between ranks can be specified, and a 'true' or natural zero point can be identified.Converted data to a lower level of measurement
Data can always be converted from one level to a lower level of measurement, but not to a higher level. Interval and ratio data can be converted to ordinal or nominal data, and ordinal data can be converted to nominal data.
Determining The appropriate level of measurement If the researcher is very concerned about the precision of the data, the interval or ratio level of measurement should be selected when possible.ContIf ranked or categorized data will be sufficient to answer the research questions or test the research hypotheses, ordinal data may be used. Finally, if categories of data are all that is called for, nominal data will be appropriate.
There are five important questions to ask when the researcher is in the process of collecting data: What? How? Who? Where? When?
What data will be collected?, the type of data needed to answer the research questions or to test the research hypothesis should be the main consideration in data collectionHow will the data be collectedSome type of research instrument will be needed to gather the data.This can vary from a self-report questionnaire to the most sophisticated of physiological instruments.
Who will collect the data?
By researchers themselves or as in scientific investigations frequently involve a team of researchers.
Other people outside the research team may also be used in the data-collection phase, sometimes data collections are paid for their services.
ContAny time more than one person is involved, assurances must be made that the data are being gathered in the same manner. Training will be needed for the data collectors, and checks should be made on the reliability of the collected dataWhere will the data be collected?The setting for data collection must be carefully determined. Optimum conditions should be soughtContIf questionnaires are being used, a researcher might ask respondents to complete the questionnaires while the researcher remains in the same immediate or general area. This procedure will help ensure return of the questionnaires.
When will the data be collected?The determination will need to be made about the month, day, and some times even the hour, for data collection.Also, how long will data collection take?Contquestionnaires will be used, they should be pretested with people similar to the potential research subjects, to determine the length of time for completion of instrument.Unfortunately, data collection usually takes longer than you envisioned.
Data collection method
Data collection methods are governed by several factors including:
The research question or hypothesisThe design of studyThe amount of knowledge available about the variable of interestContMany studies use more than one method as questionnaires ,interview ,physiological measures, attitude scales , observational methods,When several types of methods produce similar results ,greater confidence in the study findings will occurData collection instrumentsInstruments or tools are the devices used to collect data which facilitates the observation and measurement of the variables ,that determined by the data collection methods selected Great care should be taken to select the most appropriate instruments
Use of existing instrumentWhile conducting a review of literature a researcher may discover that an instrument is already available to measure the research variables ,use of the already tested instrument helps connect the present study with the existing body of knowledge on the variables Con There are many sources of available instruments to use in nursing research: Mental Measurement Year booksInstrument for clinical health care researchMeasurement of nursing outcomesThe health and psychosocial instrument
Developing an instrument
If no instrument can be discovered the researcher is faced with devolving a new instrument , it may be possible to revise an existing instrument. If any items are altered or deleted or added to an existing instrument , the validity and real ability of the tool may be altered
Pilot studyA pilot study is a small scale trial run of the actual research project A group of people similar to the study subject should be tested in condition similar to those that will be used in the actual study
The role of a pilot study:Pre test the newly designed instrumentTest a long and a short version of the instrumentTry multiple instrument that are purported to measure the same factor or constructTest various approaches for administrating the tools or instrumentsCriteria for selection of data collection instrumentPracticality of the instrumentReliability of the instrumentStability of the instrumentEquivalence reliability- Internal consistency reliability
1- Practicality of the instrumentBefore the researcher examines the Reliability of the instrument question should be askedHow much will the instrument cost ?How long will it take to administer the instrument?Will the population have the physical and mental stamina to complete the instrumentDose the researcher require special training to administer or score the instrument ?If so is this training available?ExampleIf psychological instrument such as the Minnesota multiphase personality inventory(MMPI)will be used is money available and is someone available who is qualified to analyze the data?
2-Reliability of the instrumentReliability needs to be determined whether the instrument is a mechanical device a written questionnaire or human observer ExIf you are using a thermometer to measure body temperature you would expect it to provide the same reading each time was placed in a constant temperatureWater bath
The degree of reliability is usually determined by correlation coefficients
correlation coefficients can range between -1.00 and +1.00The reliability of the instrument are expected to be positive correlationsIt frequently used when are used in a study the percentage or agreementReliability must continually be assessed the instrument is used with different subjects and under different environ mental condition
ExampleAn instrument to measure patient autonomy might be highly reliable when administered to patient while in their hospital rooms but it may be very unreliable when administered to these same patient while they are lying on a stretcher out side the operating room before surgery
3- Stability of the instrumentA - Stability Reliability of an instrument refers to over time EX If a thermometer was to be used in a study it would need to be checked for reliability before the study began and probably again during the study ( test retest Reliability )
B- Equivalence Reliability When two forms of attest are used both forms should contain the same number of items have the same level of difficulty and the