Biology population lab Questions- sept 6, 2014

Today in Biology Grade 12 class, Mr. Chung told us to do a lab called "Mark-Recapture Sampling" Lab to help us understand the method of Mark-recapture more.
It's Super fun!

1. compare your estimate of the size of the pasta population with the true size. how close were you?
 In the lab, we calculated that the population size twice, the first time the result was 1800, and the second time the result was 714,the average of them was 1257. After we counted the pasta one by one it turns out that the actual population was 615. We were 100% higher than the true population.


2.(a) What problem you think might affect the accuracy of your estimate?

For the first time, we thought that the total amount of pasta would be around 3-4 hundreds, so we took 40 of them out, and then we marked them. We shook them to mix it up.

Later on when we recaptured them, we recaptured 45 of it, but only 1 of them were marked, and we calculated the number that it has 1800 in total.(picture) We did one more trial, this time we took 100 of it, and marked it with a different mark. We recaptured exactly 100 of it and we got 14 marked, through calculation, we got that there's 714 in total. comparing to the real number, the first time was three times off, even the average was 100% off, but the second time was only  16% off. We decided to only take the second time and mark the first result as an outlier.
I think that underestimating the total population might affect the accuracy of the estimate. Because of the mistake, we captured and marked too little individuals. Also, later when we were shaking it, we only shook it for a few times, so when we recaptured, the marked ones were only in a small percentage, and made the result estimate population super big.
(b)
This activity was not completely valid in that the population was non-mobile. What problems might ecologists studying animal populations encounter?

For this Lab we did in class, we are in a controlled environment, so that we can try to count out every single one of it to gt he real population number. But in reality, scientists cannot count the real number of the population. Also, for the number of capturing individuals, there might not be enough marked ones. Since scientists must guest the real population. And that might results in a large flow in the result.

3. How might you improve your sampling design?
When capturing the sample, we need to wisely control the size, it would be good for around 15-20% of the total population.Because the first time, we only chose less than 10% of the total population, so we got a outlier. Next time, we will have to experience to guess the population before trails more clear to improve the sampling.