Statistics We have a capacity that is nearly infinite for reading evidence in the light of our own interests and passions

Outline  Dos and Don’ts of Statistics  Variables  Independent  Dependent  Types of statistics  Descriptive  Relational  Inferential

The Dos and Don’ts of Statistics  Statistics DO:  provide unbiased quantitative methods for characterizing and drawing conclusions from experimental data  Statistics do NOT:  aid determination of which research questions are important to ask  allow manipulation of data to get the answer you want  help you judge the importance of statistically significant findings

Variables  A variable is a biological trait which can take on different values for different members of the group under study  Thus, a variable is not a constant, it is a trait which varies among the experimental subjects  Examples include protein amounts, migration distance on a gel, the amount of chlorophyll in a leaf, etc.

Variables  Variables are either independent or dependent  Independent variables  Cause something to happen  Actively manipulated by the researcher,  Observed in situ by the researcher  Dependent variables  Caused by the independent variable  Experimental outcomes which are measured during a study

Descriptive Statistics  Summarize a group of numerical data  Mean  Variance  Standard deviation  Standard error of the mean  Range

Relational Statistics  Determine if two or more sets of data show any type of connection or dependency on each other  Correlation  Regression

Inferential Statistics  Compare two or more groups of numerical data to determine if they are similar or different  Compare the treatment and control groups

Activity  Pair up  Answer the questions on the next page  You have 10 minutes to do this  I will select some of you to share

1. What are the independent variables? 2. What are the dependent variables? 3. What type of statistics are presented? 4. What are the results? 5. What can you conclude from the results?