Source acknowledgement includes: Nature; The Guardian; G Van Bargen, G Brown.
Statistics: the following statistical analysis methods will be used during the data processing of experiments:
A good resource is the Handbook of Biological Statistics Statistical Tools T-test calculator Chi-square table Chi-square calculator Statistics calculator Easy Calculation Online graphing tool |
Reference Sites
Merlin statistical software link: excellent for Internal Assessments
http://www.heckgrammar.kirklees.sch.uk/index.php?p=10310 Biology Statistics Reference
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what_is_a_p_value.doc | |
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Yes, there is some math that you need to be able to do in biology....Ask for help if you cannot do any of the following as they come up. Mendellian ratios comes up second year so don't panic if you don't know what that even means.
- BAic arithmetic functions: addition, subtraction, multiplication and division
- Recognize basic geometric shapes
- Carry out simple calculations within a biological context involving means, decimals, fractions, percentages, ratios, approximations, reciprocals and scaling
- Use standard and scientific notation
- Use direct and inverse proportion
- Represent and interpret frequency data in the form of bar charts, column graphs and histograms, and pie charts
- Determine the mean, mode and median of a set of data
- Plot and interpret graphs (with suitable scales and axes) involving two variables which show linear or non-linear relationships
- Plot and interpret scatter graphs to identify a correlation between two variables, and appreciate that the existence of a correlation does not establish a causal relationship
- Demonstrate sufficient knowledge of probability to understand how Mendelian ratios arise and to calculate such ratios using a Punnett grid
- Recognize and use the relationships between length, surface area and volume.
From V VanBargen reference- temporary but very solid replacement for click4biology.
How to calculation standard deviation: Calculate the standard deviation by subtracting the mean of a distribution from the value of each individual variable in the distribution, squaring each resulting difference, summing these squared differences, then dividing this sum by the number of variables, and finally taking the square root of this quotient.
Using EXCEL to calculate the mean and the standard deviation
Also, HHMI has a nice self paced tutorial.
Using TI-83/84 to calculate the mean and the standard deviation
Using TI-INSPIRE to calculate the mean and the standard deviation
- Calculate the mean (M) of a set of data
- Subtract the mean from each point of data to determine (X-M)
- Square each of the resulting numbers to determine (X-M)2
- Add the values from the previous step together to get ∑(X-M)2
- Calculate (n-1) by subtracting 1 from your sample size. Your sample size is the total number of data points you collected.
- Divide the answer from step 4 by the answer from step 5
- Calculate the square root of your previous answer to determine the standard deviation
Using EXCEL to calculate the mean and the standard deviation
Also, HHMI has a nice self paced tutorial.
- Type the values you are trying to find the mean for in a column. You can label the column, but you don’t have to.
- Use Excel to calculate the mean of your data.
- Determine which box you want the standard deviation to appear in. In the example, I want the standard deviation to appear in box A13. Click in that box.
- Click the formulas tab at the top of the screen.
- Select the “insert function button”
- Search to find the STDEV option, click OK
- Highlight the data of which you want the SD to be calculated, click OK. Be sure not to select the mean as one of your data points for calculating standard deviation. This is a common mistake.
- Once you have the mean and standard deviation, you need to make sure that you set the values to the correct number of digits. EXCEL will default to giving you too many numbers after the decimal place. Your mean and standard deviation must have the same precision (number of digits after the decimal) as your data points. In the example to the right, since the raw data is a whole number, the mean and standard deviation must also be whole numbers. The mean would round to 133 and the standard deviation to +/- 3.
Using TI-83/84 to calculate the mean and the standard deviation
- First you have to enter the data. Hit the STAT button and you will see the options EDIT, CALC and TESTS atop the screen. Use the left and right arrows (if necessary) to move the cursor to EDIT, then select 1: Edit...
- Now you will see a table with the headings L1 and L2. Enter the values under L1 (if you want to clear pre-existing data first, move the cursor to the top of the column, hit CLEAR and then ENTER.)
- Once all the data is entered, go back to the STAT menu, but this time move the cursor to CALC instead of EDIT.
- Once you're in the CALC menu, select 1-Var Stats, then hit ENTER. The calculator will display the x-mean, some other stuff, and then the standard deviation (sx). Note that Sx is what we want.
Using TI-INSPIRE to calculate the mean and the standard deviation
- Create a new list and type your data into columns. You MUST Name your list (arrow to the top of the column and enter the name of your list). Keep the name descriptive, but short.
- Once your data is entered, hit MENU, #4 Statistics, #1 Stat Calculations, and choose #1 One-Variable Statistics.
- The choice "Open Variable Statistics" yields the following results back to the spreadsheet columns. One column will "label" these values, while the following column contains the actual values.
- remember, you want to use Sx.
what_statistical_test_should_i_use_1.pdf | |
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Nathan Green's The Guardian Statistical analysis column
http://www.guardian.co.uk/science/series/nathan-green-statistics
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