Genetic+Fish+T-test

The alternate hypothesis for this sample of captured and released fish is that the genetically altered fish are longer than the normal fish. The capture and release method is commonly used when working with wildlife and helps us make a decision with regard to the entire population of the fish in the lake. The method of capture and release is crucial, because the t-test requires random sampling. Fish were captured at different locations in the lake (I deleted the attribute for the location since it is not necessary in running the t-test).
 * Hypothesis Testing with Genetically Altered Fish (n=500)**

TikerPlots File TinkerPlots File (completed) Printout of the TinkerPlots file

Plot fish length split by type. Assign the Green fish to the genitically altered group and the Not Green fish to the normal group for purposes of scrambling the data. Plot fish length split by group. Use the history tool and select the difference of the means (in this example it is 0.2 inches in favor of the Green group).
 * Step One**
 * Step Two **
 * Step Three**
 * Step Four**

Each time the groups were scrambled, the history tool collected the difference between the means of the Green and NotGreen groups of fish. When I graphed the difference of the means of the length attributes, I had to set a range of -3 to +5.5 for the axsis in order to show the "cut score" of +5 inches. Note that in 1000 iterations, none of the differences of the means for the two groups fell even close to 5 inches. This provides evidence that I should reject the null hypothesis.

When this activity was initially posted, I made this summary statement. The length of the genetically altered fish is significantly higher than the normal fish. During a class discussion, we took a closer look and asked if this wording implies that we are accepting the alternate hypothesis, and it does. While we don't say that we "accept Ha" we can say that there is or is not enough evidence to say that it is **//probably//** true. If our claim is that the genetically altered fish are longer than the normal fish (on average), then the fact that we rejected the null means that there is enough evidence to support our claim that the mean length for the genetically altered fish is greater than the mean length for the normal fish.

This final screen shot was take from Fathom. I copied and pasted the data into a case table in Fathom. I ran a t-test to compare the means. The p-value is smaller than 0.0001 which means that the chance of having a difference greater than 5 inches due to chance is extremely rare.