Hypothesis in "Crystal Ball Math"

[danceorchestra82]

Hello,
My science fair project is the "Crystal Ball Math" experiment in the Science Buddies database. I have done extensive background research, stated my variables, and written my testable question, but I just tried to write the hypothesis and found it impossible. If the independent variable is starting population in relation to carrying capacity, and the dependent variable is population over time, how do I write a directional hypothesis? So far my hypothesis is a 2-condition statement, but I would like to find a way to simplify my variables, or even my wording, to make it shorter and simpler. My current hypothesis reads:

"If the starting population is lower in relation to the carrying capacity, then the population of silver carp will have a sharper exponential growth over time, until it reaches carrying capacity; If the starting population is higher in relation to the carrying capacity, then the population of silver carp will have a sharper exponential decay over time, until it reaches carrying capacity."

How can I make the hypothesis simple and directional, to conform to the guidelines of my fair?

[deleted-71603]

Hello. A very interesting science project, and an important one in today's world where environmental changes are drastically affecting animal populations. Great job on the dependent and independent variables.

Reference how to state a hypothesis here:
https://www.sciencebuddies.org/science- ... esis.shtml

For your hypothesis, you are on the right track. I recommend making it a little more generic. You don't need to elaborate on how each setting of your independent variable (lower than, greater than carrying capacity) will affect the outcome in your hypothesis. Keep it in the form of the simple definitions you provided in your question for the dependent and independent variables.

For example. Say I wanted to study how altitude affected the volume of a gas filled balloon. My independent variable would be altitude, and my dependent variable would be balloon volume.
Instead of this for my hypothesis: If I carry a balloon to Mt Everest, the balloon volume will be large. If I carry a balloon at sea level, the balloon volume will be small.
How about this instead: Altitude affects the volume of a gas filled balloon.

The alternative hypothesis is in the form listed on the website above "If I do this, then this will happen"....just in a different word order.

I'm not suggesting an alternative hypothesis in purpose. I'm sure you can draft an alternate on your own. How about writing back with a proposed new hypothesis or if you still have questions, and we will go from there.

I hope this helps. Good luck!

[danceorchestra82]

Thank you for the information! I have done science fair for many years in the past, but this year the project that I choose was different and more challenging. I revised my hypothesis to:

"If the starting population is lower relative to the carrying capacity, then the population of silver carp will have a steeper exponential growth in its ascent to the carrying capacity."

[deleted-71603]

I'm glad to hear you are taking on more challenging projects! Sounds like you enjoy participating in the science fairs and want to continue to challenge yourself every year.

I like your hypothesis in the form of if...then. A couple of questions.
1. I assume based on your current hypothesis, you will only test starting population that is less than the carrying capacity. Is this your intent, or would you also like to test cases where starting population is equal to or greater than carrying capacity?

2. Your current hypothesis states "the population of silver carp will have a steeper exponential growth in its ascent to the carrying capacity." Steeper compared to what?

If you intend to test all cases, you are testing one independent variable with three "levels" (starting population is less than, equal to, and greater than carrying capacity). When formulating a hypothesis, there is no need to elaborate the expected outcome for each level. You want to make a more generic statement about how your independent variable affects your dependent variable. In your case, you are changing starting population, compared to carrying capacity, to see how that affects population over time. Since you are testing many levels within your independent variable, there is no need to express in your hypothesis whether population will have steeper / same / shallower growth. A more generic statement of "will affect population growth" (or something along these lines) is sufficient.

I hope this helps. Don't get frustrated. Formulating the hypothesis can be the most difficult part of this process! Please write back if you have more questions or if you wish to propose a refined hypothesis.

Good luck!