Unit 5 biol words

Qualitative

If molecule is present (no concentrations data..)

Semi- quantative

Tells you relative concentrations of solutions but no actual value

Quantitative

Numerical values given for concentrations

Independent variable

Factor you will change /test

Dependent variable

Factor you are measuring

Controlled variables

Factors to keep constant

Minimum value of independent value changes

Record at least 5 values

Table structures

Top - Dependent variable units

Trial 1, 2, 3 MEAN

Left - Independent variable units

Value 1→ 5

Variables on y and x axsis

X - axis Independent

Y axis Dependent

When should you add range bars

3 or more repeats

Range bars definition

Show the spread of data, difference between highest and lowest

Length of range bars

Short

• Consistent and precise data

Long

• Inconsistent

What do overlapping range bars lead to

Low confidence in data

Median and mode

Middle value when arranged in order

Mode most frequently occurring value

Reliability

Consistency of results when experiment is repeated

• State whether results given are reliable (only if repeated and similar results)

• Say how to improve (repeat) identify anomolies.

Repeatability

Similar results when same person repeats experiment using the same method and equipment

Reproducibility

Ability to obtain similar results when the experiment is carried out by different people or equipment

Accuracy

How close a result is to true or accepted value

Precision

Degree of agreement between repeated measurements

Validity

Whether experiment measures what is intended to measure

Anomaly

Result that does not fit the pattern of other results

Range

Difference between highest and lowest values

Resolution

Smallest change that can be measured by an instrument

Calibration

Process of checking equipment against a known standard

Random systematic and human error

Random - cause variation and reduce precision

Systematic - consistently inaccurate due to faulty equipment or method

Human - Mistake by experimenter

How to improve validity

Larger sample

Control variables

How to improve accuracy

Smaller divisions of equipment

More precise

Reduce systematic errors

Improve precision

Repeats

Higher resolution

Reduce random error

Improve reproducibility

Different people repeat experiment

Different equipment

Share clear method

Improve repeatability

Same person repeat

Same equipment and method

Follow method carefully

Improve reliability (consistency)

Repeat experiment

Calculate a mean

Remove anomalies

Improve validity of conclsuion

More data points

Wider range

Repeat

Improve strength of Conclusion

Strong correlation and trend

Large data set

Consistent results

Improving inaccuracies

Better equipment use in method

• Smaller resolutions (precise) smaller divisions

• Give thermostatically controlled water bath, pH buffer…

GIVE IMPROVEMENT

Measuring length improve accuracy?

Ruler

• Callipers measure object (better resolution 0.5mm)

Measuring volume

Syringes not accurate only cm³

Graduated pipette better resolution for accurate reading

Measuring subjective colour change

Colorimeter measure transmission or absorbance by liquid giving digital reading

Measuring pH

USE BUFFER - maintain pH

Indicator liquid or paper - Subjective

Electronic pH meter accurate quantitative data

Measuring temp

THERMOSTATICALLY CONTROLLED WATER BATH - Control temp

Electronic - or any with better resolution smaller divisions

3 Parts of risk assesment

Nature of hazard

Risk to person

Safety measure to reduce

• NaOH Corrosive

• Damage skin WHEN POURING BEAKER

• Wear goggles..

Calibration curve function

Deter