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Data Objectives
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Objectives you identify at the outset of an experiment orscientific study to help determine the nature, amount, andquality of the data you (or someone else) need to collect toanswer the questions you are asking with the necessary levelof certainty
(You can think of data objectives as data collection objectives or data quality objectives, or anything else, as long as you understand their purpose.) ¾ The same process can be applied to determine how muchsimplification is appropriate when describing ageochemical system.
To conduct scientifically defensible research… You need to establish qualitative and quantitative measures or guidelines to determine whetherdata is sufficient and sufficiently accurate to draw a conclusion regarding a specific problemor to answer a specific question.
Data objectives will help you: determine when, where, and how many samples ormeasurements to collect and determine the desired level of confidence in the data needed tojustify your interpretation of the data and explain ageochemical system Developing data objectives is really part of the scientific method.
You will need to:
Summarize the overall objective of the study and the problemfor which additional data is needed. - Identify the questions that the study will attempt to answer. - Identify the type and quality of the data needed to answer thequestion with the level of assurance that you believe isnecessary. - Identify the spatial and temporal boundaries for the system thatyour data is intended to explain.
Why are data objectives important? Evaluate existing data relative to your data objectives before youbegin your study Incorporate usable data into the initial geochemical model Identify gaps in the data set Determine significance of data gaps relative to data objectives Design and implement a sampling plan that will meet your goals
Example geochemical questions that data objectives can help you answer: What data are needed to determine chemical inputs to the lake? Would three samples of lake water be sufficient to determine waterchemistry in the lake? Would 50 samples be necessary? Whatchemical analyses should be performed or what chemicalparameters should be measured? Is the time-frame over which sampling was conducted sufficient?Should samples be collected at various depths in the lake toadequately characterize the chemical characteristics of the lakewater? Can I assume that the effect from biologic organisms will be smalland not affect my results enough to change an interpretation?
Developing Data Objectives
- Identify and understand each question or issue you hope to address. - Review prior studies and existing information to gain an understandingof the geochemical system and the issues to be addressed - Summarize the questions that require new data to be collected - Describe overall study objectives - Outline scientific decisions or interpretations that will be made based onthe data, and identify the importance of data of each type to makingthose decisions or interpretations - Identify resources available to address the issues
- Identify interpretations/conclusions that will be made with respect to each geochemical question or issue. - Identify the types of interpretations/conclusions that will bemade using the data - Determine degree of certainty that is necessary for each datapoint
- Define the study boundaries (i.e., specify the spatial and temporal aspects of geochemical system that the datamust represent to support the conclusion/interpretation). - Define the geographic area or physical boundaries of theinvestigation. - Define the media of interest. - Specify the time-frame and range of conditions over whichsamples will be collected.
Develop guidelines to help interpret the data and torecognize when the data collected is enough to answer thequestion with the level of certainty you needed.
Consider the conditions that would cause you to chooseamong alternative interpretations and/or take differentdirections to interpret the data. - Consider the factors that will help you decide when enoughdata is enough and the additional cost of collecting more datais unlikely to affect your interpretations or conclusions.
Using Multiple Lines of Evidence Because there is inherent uncertainty in any geochemical data set, you can improve the level of confidence in yourinterpretation if you have several lines of evidence thatsupport your hypothesis. Usually, you will need to consider the different types of data you need before you start collecting any data. Other times, in the process of collecting data a pattern will emerge suggesting additional types of data that might be valuable to collect.
Assignment
Due Monday, September 15
th Read “arsenic in groundwater” paper Answer questions on handout sheet
