Forensic science laboratory manual

Rather, it is a fact that all scientific measurements of a quantitative nature are imperfect and have an uncertainty associated with them. The goal of scientists is to do their utmost to decrease this uncertainty as much as possible. Here we mean the errors that occur due to imperfections in our apparatus, its calibration, or random variation due to our inability to reproduce a particular portion of the procedure being used to make the measurement. The determination of the total uncertainty of a measurement is not necessarily a simple matter.

As an introduction, we will present a number of basic concepts in this experiment with the goal of demonstrating them in the laboratory exercise. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment.

Notify me of follow-up comments by email. Notify me of new posts by email. Table of Contents. Objective: To make available a safe and academically beneficial environment in the forensic laboratory by promoting safety and alertness.

The student will become familiar with the collection of scientific data and the performance of measurements. The student will learn about the basis for the uncertainty in measured values and the types of error that can arise. He or she will make a number of measurements and determine values based on these measurements. Each student will perform a number of basic statistical calculations and compare the data obtained from a single experimenter and data obtained from a group.

The purpose of this experiment is to demonstrate the uncertainty of scientific measurements due to a number of possible errors in the measurement process. First, the student will make a number of measurements, including length, weight, and liquid volume determinations. Second, the student will determine the variation in measurements of the same items by multiple students.

The student will, as an option, determine the standard deviation variability of these measurements. Third, as an additional optional exercise for this experiment, the student may determine the density of glass by measuring the mass and volume of glass shards. There are three general classifications of error by scientists. Some have subdivisions.

These are systematic, random, and gross errors. All the items we mentioned above as mistakes, as well as inattention to reading a value from an instrument, misweighing a sample, and others all fall into this class. The cause of the error, in most cases, unless noticed and reported by the analyst, cannot be traced. The only way to ensure that a blunder has not taken place is to make several measurements or determinations. If a blunder takes place, the suspect value will appear very different from the others.

Arithmetic miscalculations and data entry errors into spreadsheets are exceptions to this rule of multiple determinations, but some type of hard copy record must be available for examination to reveal the origin of these errors. If downloading failed then please refresh the page or try later after sometimes.

Sometimes due to large amount of traffic server goes down. Information about your use of this website will be shared with Google and other third parties. Read our privacy policy. Help learners to visualise the shape and structure of simple covalent molecules with these manipulative covalent bonding tiles.

Name common amino acids and draw the structural formulas of dipeptides and tripeptides in this resource for year old learners before considering how thin layer chromatography can be used to separate and analyse amino acids in a mixture.

Site powered by Webvision Cloud. Skip to main content Skip to navigation. No comments. Pre laboratory exercises and laboratory practicals in Forensic Analysis. Download all. Use Practical experiments Handout Download.