Today: Chi2, Inquiry 2 and Lab Safety...

http://www.eurofins.com/media/19528/es_breda_lab_overview.jpg

The Chi Square Test

• A statistical method used to determine goodness of fit– Goodness of fit refers to how close the observed data

are to those predicted from a hypothesis

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Two flies with different traits are bred together

Out of 352 offspring 193 straight wings, gray bodies 69 straight wings, ebony bodies 64 curved wings, gray bodies 26 curved wings, ebony bodies

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

According to our hypothesis, there should be a 9:3:3:1 ratio of fly offspring

Phenotype Expected probability

Expected number

straight wings, gray bodies

9/16 9/16 X 352 = 198

straight wings, ebony bodies

3/16 3/16 X 352 = 66

curved wings, gray bodies

3/16 3/16 X 352 = 66

curved wings, ebony bodies

1/16 1/16 X 352 = 22

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Apply the chi2 formula

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Interpret the chi square value The calculated chi square value can be used to

obtain probabilities, or P values, from a chi square table

These probabilities allow us to determine the likelihood that the observed deviations are due to random chance alone

If the chi square value results in a probability that is less than 0.05 (ie: less than 5%)

The hypothesis is rejected

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Interpret the chi square value

Before we can use the chi square table, we have to determine the degrees of freedom (df)

The df is a measure of the number of categories that are independent of each other

df = n – 1 where n = total number of categories

In our experiment, there are four categories Therefore, df = 4 – 1 = 3

1.06

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Interpret the chi square value With df = 3, the chi square value of 1.06 is slightly

greater than 1.005 (which corresponds to P= 0.80)

A P = 0.80 means that values equal to or greater than 1.005 are expected to occur 80% of the time based on random chance alone

Therefore, it is quite probable that the deviations between the observed and expected values in this experiment can be explained by random chance

Spreadsheet applications will compute chi2

Is the male:female ratio in the CNS different from the general population?

Inquiry 2 -Who?

•Groups of 3-5 people

Inquiry 2 -Who?

•Groups of 3-5 people

•Divide work

Inquiry 2 -Who?

•Groups of 3-5 people

•Divide work

•Be clear about responsibilities and expectations

•Leave enough time to get everything done without panic

Inquiry 2 -What?

Incredibly, amazingly, fantastically, critically important, essential information has been posted on the class webpage and the FRI-rm webpage (https://fasttex.diia.utexas.edu/fri-rm) about:

•Lab Safety

•Supplies

•Order Forms

•Updated Proposal and Report Formats

Inquiry 2 -What?

•May use gadgets, chemicals, kits, etc

-https://uteach.utexas.edu/direct

-Analytical/physical chemistry storeroom(order on website)

-Media kitchen (via chem storeroom)

-Research Streams

To submit an order you need to know your unique number... and

Your order must include disposal information.

CAS registry numbers:

unique identifiers for most chemicalshttp://www.cas.org/expertise/cascontent/registry/regsys.html

Inquiry 2 -What can you not do?

•No experimental manipulations on vertebrates, observations are fine.

•No collection of wild-type microorganisms, bacteria and/or yeast

Inquiry 2 -What can you not do?

No experimental manipulations on vertebrates, observations are fine.

•No collection of wild-type microorganisms, bacteria and/or yeast

Similar limits to inquiry 1:

•3 weeks from proposal to report

•Safety is the #1 priority

Inquiry 2 -Where and When?

You can work in lab during your scheduled lab times, and/or during my other lab times.

M 12-3pm

M 3-6pm

Th 12:30-3:30pm

Th 3:30-6:30pm

Inquiry 2 -Where and When?

You can work during the your scheduled lab times, and/or during my other lab times.

Outside of lab times, you may only work when a TA is present. These times will be posted weekly.

Inquiry 2 -Where?

Lab Safety

Inquiry 2 -Where?

Lab Safety

•Closed toed shoes, sleeves, long pants, hair out of harms way

Inquiry 2 -Where?

Lab Safety

•Closed toed shoes, sleeves, long pants, hair out of harms way

•NO FOOD in lab

Inquiry 2 -Where?

Lab Safety

•Closed toed shoes, sleeves, long pants, hair out of harms way

•NO FOOD in lab

•Be aware of what you are doing and working with

Inquiry 2 -Where?

Lab Safety

•Closed toed shoes, sleeves, long pants, hair out of harms way

•NO FOOD in lab

•Be aware of what you are doing and working with

•Wash hands before leave lab

Inquiry 2 -Where?

Waste Disposal

You are responsible for the safe disposal of all waste you generate.

Waste disposal is one of the most dangerous things that we do in lab.

Inquiry 2 -Where? Waste Disposal

Inquiry 2 -Where?

Waste Disposal

You are responsible for the safe disposal of all waste you generate.

This includes chemical waste and biological waste.

If you make a mistake, spill something, have an accident… tell someone immediately.

http://www.time4science.com/images/labsafety/labsafety2.JPG

Inquiry 2 -How? Proposal

Mostly the same as inquiry 1

2 additional parts

Inquiry 2 -How? Proposal

Mostly the same as inquiry 1

2 additional parts

In the Experiment section

Include detailed information on equipment and reagents to be used.

Where will you get them?

After your proposal is approved, needed order forms filled out online.

Inquiry 2 -How? Proposal

Mostly the same as inquiry 1

2 additional parts

Add a Responsibilities sectionDescribing your plan for whom will do what…

Inquiry 2 -How? Proposal

Proposals will not be approved until sources for all equipment and/or chemicals are secured.

Orders will be placed during lab, after your proposal is approved.

Inquiry 2 -How? Written Reports

Similar to inquiry 1, but add a Responsibilities section

Inquiry 2 -How? Written Reports

Similar to inquiry 1, but add a Responsibilities section

Everyone should participate in writing, some may write the original text, while others work on figures/tables, and others edit.

Inquiry 2 -How? Oral Reports

•Should be 15 to 20 minutes long

Inquiry 2 -How? Oral Reports

•Should be 15 to 20 minutes long

•Include all of the basic information from the written report.(Do not simply read your written report)

Inquiry 2 -How? Oral Reports

•Should be 15 to 20 minutes long

•Include all of the basic information from the written report.(Do not simply read your written report)

•Everyone will present some part of the oral report

Inquiry 2 -How? Oral Reports

•Should be 15 to 20 minutes long

•Include all of the basic information from the written report.(Do not simply read your written report)

•Everyone will present some part of the oral report

•Should be visually engaging

My group sucks, and now I am going to fail.

Don’t have a cow man.Your will be graded as agroup and also only on

your sections.

Inquiry 2 proposals are due in lab on Th 9/30 or M 10/4

Homework #3 due now:What was the hardest part of inquiry 1, and how will you make this easier for inquiry 2?

This weekend: Pecan Street Arts Festival(http://www.oldpecanstreetfestival.com)

Stream open house ongoing (homework #2)

Next week: Research Ethics