# Bio lab 13 Feb 12 2010

Bio lab 13

Measurment error reflects the discrepancy between our repeated measurment and the ture value of

the object being measured.

Precision and accurancy:

Precision t is the repeatability of the measurement.

If a single measurement when repeated shows little little variation, it ahs high precision, if it shows great

variation, it has low precision

Accurancy t is the tendency for the measured value to be close to, or apporximate, the true accepted

value.

Significant figures~

Measurement contain three parts t unit, scale factor and significant figures

Scientific notation~

Rounding numbers:

Less than 5 unchange~

Larger than 5 roung up

5 t before is even t unchange odd t roung up

Organized data:

Qualitative: such as hair colour, sex or something something are easy to group

Quantitative t discrete and continuous

Use a table or a figure to presenting data

Dependent variable plot on y-axis, and independent variable plot on x-axis

Line of best fit: a line which travels through the space pccupied by most of the points

Interpolation: line of best fit allow us to predict the data that is not one of the plot points

Extropolation: extending the line beyond the existing data t provide the base for prediction

Bar graph t used for discrete data

Historgram t used for continuous data

Statistics of location: describe the position of a sample along a given dimension.

Most common statistics location t mean, median and mode t usually called the measures of central

tendency.

Mean: calculated by divide the sum of the data by the number of individuals involve in the experiment

Median: middle value t odd number t the middle; even number t divided the middle two by 2.

Mode: the most frequently appear data

Note: median will become a better estimate of central tendency than mean under the situation that

there are some extreme data which tend to bias the mean in their direction.

Statistics of dispersion t variabiliy, used to describe how broad the set of data could be, narrow or wide

t simplest form t the range

Most common ~ vatiance and standard deviation and standard error

Range: the difference between the largest data and the smallest

Variance: measyre of how much scatter there is around the mean

Standard deviation: the square root of variance t average size of the deviation from the mean, symbol -s

Standard error: measure how reliable the sample mean is as an approximation to the population mean.

^AlOv

^µv[-test and chi-square test:

t-distribution: a distribution of the differences between two samples which are taken from the same

population that we can obtain simply by chance.

Bell-shaped and symmetrical t-distribution

This test is used to compare the means of two samples and assesses whether or not they differ enough

to represent samples from different population.

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## Document Summary

Measurment error reflects the discrepancy between our repeated measurment and the ture value of the object being measured. Precision j is the repeatability of the measurement. If a single measurement when repeated shows little little variation, it ahs high precision, if it shows great variation, it has low precision. Accurancy j is the tendency for the measured value to be close to, or apporximate, the true accepted value. Measurement contain three parts j unit, scale factor and significant figures. T 5 j before is even j unchange odd j roung up. Qualitative: such as hair colour, sex or something something are easy to group. Use a table or a figure to presenting data. Dependent variable plot on y-axis, and independent variable plot on x-axis. Line of best fit: a line which travels through the space pccupied by most of the points. Interpolation: line of best fit allow us to predict the data that is not one of the plot points.