1. Basic Statistics For Science Fair
Image from:
Basic Statistics
For Science Fair

2. Which Graph do I Use? Line Graph
Graph Type
When do I use it?
Line Graph
When both the dependent and independent variables are quantitative (numbers).
Bar Graph
When one variable is qualitative (observed, example: color).
Pie Chart
When you are looking at a % (part of a whole)
Scatter Plot
When both variables are quantitative (numbers) and you are comparing the effect of one on the other (example: how body temp. effects heart rate).
Histogram
When both variables are quantitative and one is expressed in a range (example: age ranges)
Which Graph do I Use?

3. Why do we Need to do Statistics?
When we do experiments it is not usually possible for us to test every member of a population. Example: How does acid rain affect plant growth? (we can’t test every plant in the world)
We can however, test samples of a population. Example: How does acid rain effect the 50 plants in my sample?
Statistics helps us figure out how are sample will apply to the whole population. Example: 75% of our sample experienced reduced growth. Does this show that plants in areas where acid rain is present will grow 75% less?
In a nut shell, statistics allows us to determine if what happens to a small part of a population will happen to the larger population.

5. Statistics We May Be Farmilar With?
N=population
n= sample
mean (average)
Median (midpoint)
Range= difference between extreams
Degrees of freedom= n-1

6. Let’s Try In Excel!

7. Standard Deviation

8. Calculating Standard Deviation
Ages of Students in my class room 14 15 16 17

9. n

10. Standard Error

11. Pennies Lab Get two pennies .
Drop water drops on the first one and record how many drops you get on the penny before it over flows. (Do this 5 times).
Cover the second penny in soap and then follow the same procedures above.
Create a data table in Excel and calculate, Mean, Standard Deviation and Standard Error.
Create a graph.

12. Chi-Squared Test

13. Null Hypothesis
The null hypothesis represents an idea of no difference and is labeled by the symbol H0.
The “normal” hypothesis is called the alternative hypothesis and is labeled by the symbol Ha.

14. Example:
Ha: Given the choice between white and green bread female mallard’s will prefer the green bread.
H0: Given the choice between white and green bread female mallard’s will be indifferent.

16. Let’s Try In Excel!

17. Degrees of Freedom
n-1
n=sample size
A + B=10
A+ B + C=10

18. Chi Squared and M & Ms Open your bag of M & Ms.
Count the total number of M & Ms.
Divide by 5 to get the expected value of for each color.
Write a null hypothesis for your M & Ms.
Separate your M & Ms by color and count how many you have of each color.
Create a table in excel
Calculate the chi-squared for your data.
Was your null hypothesis accepted or rejected?