1. Introduction to Descriptive Statistics Anna Ortiz 2015

2. What is Statistics?
The collection and analysis of data to understand trends and behaviors of processes…

3. Types of Data Data= plural Quantitative ? Datum= singular Qualitative?
DATA ARE….
DATA IS…
Quantitative ?
Information based on quantities
Qualitative?
Based on a characteristic
Continuous?
Think about decimal places
Categorical?
Think about groups of things

4. EXAMPLES

5. Today you will do a regression
It is a model of the relationship of an explanatory variable on a dependent variable.
X defines Y
Y depends on X
It tries to fit a straight line between all of your data points
R2 is the strength of the relationship.
It ranges from 1 to -1, it explains percentage explained Y.

7. You will vary the number of gummy bears/worms you shoot
Hypothesis: The more/less gummies we shoot the further/closer they will reach from the base of the catapult
You will need replicates
5 minimum per category (# of gummies)
Then average, variance, standard deviation
Mass of gummy bears and number of gummy bears (g)
Measure distance with ruler (cm or m)

8. Build catapult Each group will need 2 clothes pins 6 popsicle sticks
~15 rubber bands
2 black binder clips
One spoon
5 gummy bears

9. Should take no more than 10 minutes to build catapult

10. Was your hypothesis supported?
Share data
At the end we will share data on the computer so that everyone can analyze it
AVERAGE DISTANCES /#GUMMIES
Was your hypothesis supported?
Lets see if your predictions match your model!

11. Basic Descriptive Stats
Mean (average) = the sum of all values divided by the number of values
Range= the distance between the largest and smallest value
Standard deviation= how spread out the numbers are from the mean
WHAT IS THE DATA TELLING YOU?

12. Standard deviation Stdev= square root of the variance
What is variance?
The average of the squared differences from the mean….

13. What are the descriptive statistics for you data set?
Mean =average()
Range =range()
Standard deviation =stdev()
Regression
Make a bar graph for each category ( how many pieces of gummy worm) and distance
X and Y variables
Was your hypothesis supported or not supported?