How Valid is the data?

1. How Valid is the data?

2. Objectives • Choose an appropriate sampling method (B) • Explain that the sample size is important if the results are to be considered valid (C) • Describe how some variables can be controlled. (C) • Explain why it is difficult to control all the variables in fieldwork. (B)

3. Reproducibility and Validity • Think, pair, share- what do these two words mean? • Reproducibility- the ability for others to duplicate or repeat an investigation and receive similar results to you • Validity- the question being investigated can be answered Glossary terms If you used 10 quadrats instead of 100 would it be as reproducible or valid?

4. Factors affecting reproducibility and validity? • List the different factors that may affect how reproducible and valid an investigation is • Sample size • Do you want to record the number of organisms in a given area? If so, random quadratswould be best • Do you want to measure change in distribution over a range of habitats? A transect would work best here • Method of sampling • Can your method be used by everyone? • Will your method work all year round?

5. Variables • What are they? • Describe the three main variables • Independent (thing you change) • Dependent (thing you measure) • Control (thing you keep the same) • Using the investigation we did outside – what are the variables?

6. Sample size • Would it be practical to sample everything when doing a study? • If we were looking at humans – could you sample everyone?

7. How are conditions different when investigating a hypothesis in the lab to when you are outside?

8. Answer: • What do: Reproducibility and validity mean? • What will affect whether an experiment is reproducible or valid? • What factors affect sample size? • What are variables? • How will these variables be different inside and outside of the lab?

9. A penguin case study by Professor Boersma Read the information on the handout and answer the questions in your books

10. Answer the exam questions

11. Can you? • Choose an appropriate sampling method (B) • Explain that the sample size is important if the results are to be considered valid (C) • Describe how some variables can be controlled. (C) • Explain why it is difficult to control all the variables in fieldwork. (B)