Independent and Dependent Variables

Quiz 1 Study Guide – ANSWER KEY 1. Lab Safety – Know the rules and guidelines 2. What are the six steps of the scientific method? Make an observation… ask a question, do background research, construct a hypothesis, experiment, analyze data, conclude & communicate 3. Be able to define the different variables in an experiment: ‐ Independent: Factor the scientist is changing/manipulating/controlling ‐ Dependent: Factor(s) the scientist is measuring (in response to the change) ‐ Controlled: Things that stay the same 4. Identify the variables for the following scenario: A social psychologist thinks that people are more likely to conform to a large crowd than to a single person. To test this hypothesis, the social psychologist had either one person or five persons stand on a busy walking path on campus and look up. The psychologist stood nearby and counted the number of people passing by who also looked up. Independent variable: number of people standing and looking up (1 vs. 5) Dependent variable: number of people passing by who also looked up (counted) Constants or Controlled variable(s): Time of day, weather, etc. 5. Identify the variables for the following scenario: A group of college students were given a short course in speed‐ reading. The instructor was curious if a monetary incentive would influence performance on a reading test taken at the end of the course. Half the students were offered $5 for obtaining a certain level of performance on the test, the other half were not offered money. Independent variable: +/‐ Monetary reward Dependent variable: Score on a reading performance test Constants or Controlled variable(s): reading level 6. Types of Observations (quantitative, qualitative, objective, subjective). Identify whether the following observations are quantitative/qualitative and objective/subjective. a. It was 98⁰C in the gym. Quantitative/Objective d. The Patriots are the number 1 team. Quan/Subj b. The basketball court was 32 meters long. Quan/Obj e. The uniforms are sky blue. Qual/Subj c. The basketball was round and orange. Qual/Subj 7. Types of measurement – be able to identify the base unit (in the metric system) for each. Identify whether the following units are a measurement of length, mass, volume, time, or temperature. a. A 55.0 g sample was placed into a paper bag. mass b. The water measured 273 K. temperature c. A large piece of cake occupies 115 cm3. volume d. Sarah ran for 15 minutes. Time e. Jeff measured out 710 mL of sodium chloride. volume f. Nick crossed the stream where it was the narrowest, only 1.5 m. length 8. What is the difference between a data table and a graph? What are the “rules” for creating a data table? What are the five main parts of a graph? Data Table: For organizing data Must have: Title, Date, use a ruler, Independent variable in the 1st column Graph: For summarizing/showing patterns Must have: Title, Key, X‐axis with labels/units, Y‐axis with labels/units, Even increments, Ruler 9. A precipitation reaction occurs when you mix solutions of silver and bromide. A scientist wants to see the effect of adding extra silver to the equation. On Tuesday she adds different concentrations of silver solution to a 1.0 M bromide solution and finds the mass of precipitate formed. When she adds 15 g/mL of silver, 24 grams of precipitate are formed. When she adds 25 g/mL of silver, 38 grams of precipitate are formed. When she adds 40 g/mL of silver, 50 grams of precipitate are formed. When she adds 50 g/mL of silver, 61 grams of precipitate are formed. a. Create a table data for this information. – include all components! Data Table 1: Effect of Silver on Silver Bromide Formation Date: August 4th, 2015 Concentration of Silver (g/mL) Mass of Silver Bromide Formed (g) 15 24 25 38 40 50 50 61 b. Create a scatterplot graph for this information. – include all components! *** A key is not needed because you only have one data set