Lab 1 Scientific Method

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University of Cincinnati, Main Campus *

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1015

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Statistics

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Apr 3, 2024

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Lab 1: Scientific Method The scientific method is the accepted format for investigating a problem. The process includes collection and integration of data to produce an informed conclusion. Steps of the scientific method are observation, hypothesis, prediction, experiment, and conclusion. An observation is a question about the natural world. By researching your question, one can come to a hypothesis , or a tentative answer to the question. From that answer, a scientist can form a prediction , which is an “if ……. then” statement that demonstrates the outcome deduced (if [state the hypothesis] then the results will be…). A controlled experiment can be developed to test the prediction. A controlled experiment has several different variables including the independent variable, dependent variable, and controlled variables. The independent variable is the factor in the experiment that is being changed. A well-developed experiment contains only one independent variable. The dependent variable is what is being measured in the experiment. The control variables are factors in the experiment that are constant and are given to both the control and the experimental group in the experiment. The control group does not receive the independent variable and is what the experimental group is compared. The experimental group has all the same variables as the control group in addition to the independent variable. For an experiment to be successful, the experimenter needs to have replication , meaning usually three or more test subjects in the control and in the experimental group. Experiments will produce data; that data can be either quantitative (numbers) or qualitative (descriptive) . Examples of quantitative data include measurements such as weight, height, blood pressure and heart rate.

Hypothesis/Prediction Observation Disprove hypothesis Support hypothesis Experiment Conclusion/Theory Qualitative data would be observation such as taste, color, smell, and appearance. Data can be summarized by performing statistic (mathematical calculations) on the numbers. Some common statistical calculations used in data analysis are the mean (or average), median and standard deviation. The mean is calculated by summing the individual values and dividing by the number of values in the data set. The median is the midpoint between the highest and lowest values in the set. The standard deviation describes how spread apart from the average the values are. The higher the standard deviation, the more spread out are the values. Standard deviation is a complicated equation. You will be directed to a video tutorial describing this calculation, but then you will rely on Excel to calculate these numbers. Once the data is collected, it can be analyzed, and conclusions can be formed. The experimenter must determine if there is support or disproval of the hypothesis. 2

Part I: Step by step through scientific method To help you understand the terminology presented above, answer the following groups of questions. Hypothesis : Scientist must be able to develop an experiment that is rooted in scientific learning. In the following hypotheses, first determine if these are testable hypotheses, place ‘yes’ or ‘no’ in the blank. If they can be tested, indicate the independent variable, dependent variable, and develop possible controlled variables (Recall the definition of these terms are in the above paragraphs) within this experiment. 1. Plants exposed to sunlight will grow taller than those that are not in sunlight. Scientific hypothesis? _____yes______ Control variables __taking away sunlight/ giving more sunlight __Independent variable _______sunlight increasing vs. decreasing __Dependent variable __plants being measured 2. Dogs love their owners because they wag their tails when their owners approach. Scientific hypothesis? _____yes_____ Control variables ______________if dogs wag due to their owners ___________________Independent variable ______tails wagging ________________ Dependent variable _________dogs ____________ 3. High blood pressure is a result of large amounts of cholesterol in the diet. Scientific hypothesis? ______yes____ Control variables ________________adding cholesterol to diet vs. none __Independent variable _________Blood pressure ___ Dependent variable __________Diet 4. People who eat breakfast before an early morning test will have higher scores than those that do not. Scientific hypothesis? ____yes______ Control variables ____________test taking in the morning _____________________Independent variable ________who eats breakfast/ who doesn’t in morning ______________ Dependent variable _____test scores ________________ Part II: Types of Data You will generate class data on which to perform some descriptive statistics. Methods: Submit the following information directly to the class web site anonymously. Age, gender (male or female), weight (in pounds), height (total inches) A data table of this information will be made available to the class. 3

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Enter the class data into an Excel spreadsheet. For the quantitative data, calculate the mean, median and standard deviation. If you are not familiar with Excel, see the separate handout that will walk you through the steps of data entry. (This should be set up as table 1) Summary: 1. Answer the following questions using complete sentences: a. How many females and how many males are in the class? Is the classification data of “male” or “female” qualitative or quantitative? Explain your answer. b. Create a table that shows the data summaries for the quantitative data collected in Part A. Your table should have a number (i.e. Table 1) and a descriptive label. Units should be included. Follow the example below. Table 1. Descriptive statistics for Introduction to A&P lab students in section 001. Parameter Class Mean Class standard deviation Class median Age (years) Weight (pounds) Height (inches) 2. Describe 2-3 interesting observations about our class. 3. Part III: Scientific Method in Action Materials: Vinegar (about ½ cup) Saltwater solution Baking soda solution Lemon juice Water One other liquid of your choice Note: You can create your solutions by adding one Tablespoon of substance to ½ cup of water and stirring. You will need about ½ cup of each liquid. Methods: You will be testing for a chemical reaction with vinegar. Add 1 Tablespoon of vinegar to each of the liquids and record the result. You will write “fizzing” if you saw bubbles form or “no reaction” if nothing happened. 4

Sample Data Table: Table 2: This table shows the results when various liquids were mixed with vinegar. Substance Reaction Saltwater solution No reaction Baking soda solution reaction Lemon juice No reaction Other substance Borax No reaction Summary: 1. Create a data table for Part B (follow the sample given above in the Methods section). Include a table number and descriptive label. 2. qIs the vinegar reaction qualitative or quantitative data? Explain your answer. r\ 3. Re-create the (or copy/paste) the data table below and fill in the words “qualitative” or quantitative to describe the data. Table 3. Examples of quantitative and qualitative data. Data description Qualitative or quantitative Emily’s takes 15 breaths per minute. The sky turns a dark blue during thunderstorms. That cheese has a strong taste. I have 3 ounces of cheese. 4. Calculate the mean, median and standard deviation for the following test scores: 49, 70, 54, 67, 52, 75, 98, 86, 73, 88, 91, 80, 61, 77, 82 5

Lab 1 Scientific Method

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