IB Data Analysis Practice 1

In this activity, you will practice creating the most common graph used in IB Biology, the scatter plot.  Additionally, you will conduct a correlation test and use standard deviation to depict the degree of uncertainty in the data.  It may be helpful before, during, or after completion of this activity to examine the explanation of IB Lab Standards that outlines the specific requirements for each component of the Data Collection Standard.  They can be found here.

Part A: Creating a Table

1. Create a table like the one below in Excel.
2. Tables should be arranged so that rows/columns are labeled.  All rows/columns must have units, uncertainties, and units.
3. All tables must have a title that specifically indicates what is being presented (this one is done for you).
4. Tables are generally arranged in this manner so to make calculations easier in future steps.

*The mass for each bird sample (1-5) is being measured per beak length (12-16mm) so the numbers under (12-16mm) are the mass measurements for each bird.

Part B: Calculating Mean and Standard Deviation.

Excel makes it extremely easy to calculate mean and standard deviation very quickly for large data sets.  Calculate both mean and standard deviation of these in Excel (don’t use a calculator) by watching the following video:

Calculating mean, median, mode, and standard deviation in Excel.

Part C: Creating an X-Y Scatter Plot Graph.

An X-Y Scatter Plot graph allows two numerical data groups to be compared with one another.  For example, how does the mass of birds compare with their beak length.  In this example, and for nearly every data collection opportunity, there will be multiple trials for each variable.  In this case there are five different beak lengths identified and five bird mass samples for each bird beak length.   Using the calculated mean, create an X-Y scatter plot graph for the sample data using the following video:

How to create an X-Y scatter plot graph

Part D: Creating Error Bars on an X-Y Scatter Plot Graph.

Anytime data is collected for a number of samples of the same category, there will almost always be variation in said data.  By using standard deviation, one can calculate standard of the mean as a way to indicate the reliability of measurements as an indicator of the true mean for the entire population.  Using this value and a confidence interval of 95% can be used to show, with 95% confidence, what values would the true mean would be expected to fall within.  Using the calculated standard deviation, standard error of the mean, and 95% confidence interval, add error bars to your graph after watching the following videos:

How to calculate Standard Error of the Mean & 95% Confidence Interval

How to create Excel Error Bars using 95% Confidence Interval

Part E: Creating Linear Regression Correlation Test

A correlation test can indicate the correlation or degree of relatedness between two data sets.  As discussed in class, this is merely a suggestion and does not necessarily prove two data sets are correlated.  However the test can be useful and will be used throughout IB Biology.  For example, a correlation test could indicate the relatedness between bird beak length and mass.

A correlation test can be accomplished in Excel by adding a line of linear regression; it is also possible to add lines of polynomial regression which may be useful for data sets that both increase and decrease rather than just one.Using the same graph and data, add a linear regression line and R2 value to indicate the correlation between bird beak length and mass in which the R2 value is the correlation value by watching the following video:

How to create Excel Linear Regression

Part F: Turn-In

Printing graphs and spreadsheets from Excel can sometimes be just as challenging as creating them.  You will turn this assignment in by inserting images of the data tables and graph and  onto this document on two different pages.  One page will include only the graph, the second only the data table (I just want you to have practice doing both for future when data tables get really big).

Complete this task by watching the following video.

Printing & Organizing Data Tables & Graphs from Excel