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Lecture

Bio lab 13 Feb 12 2010

by OC4

Department
Biology
Course Code
BIO120H1
Professor
Ingrid L.Stefanovic

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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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