Lifescience 1

Variable Placement

  • Dependent variable: y-axis

  • Independent variable: x-axis

Calculations

Averages

  • Formula: Add samples / number of factors

  • Example: (10A-40 + 10B-35) = 112 - number of samples

Percentage

  • Formula: (Value / Total) x 100

  • Example for 10B (35): (35 / 112) x 100 = 31.25%

Percentage Increase/Decrease

  • Formula: (Difference / Original value) x 100

  • Note: Indicate "increase" or "decrease" after % sign

Ratios

  • Simplify ratios

  • Example: 80.2 : 4 becomes 1:2

Total Magnification

  • Formula: Eye piece magnification x Objective lens magnification

Histograms

  • Connected bars showing continuous data

  • Used for independent variables that fall into categories

Pie Charts

  • Circular charts for comparing parts of a whole

  • Used for discontinuous data

Scientific Investigations

Key Terms

  • Observation: What scientists saw that prompted investigation

  • Aim: Investigate relationship between two variables

  • Independent Variable: Manipulated variable on X-axis

  • Dependent Variable: Responding variable on Y-axis

  • Controlled Variables: Remain constant for validity

  • Control: Comparison setup without the tested variable

  • Accuracy: Care in measurements

  • Validity: Appropriateness of method

  • Results: Evidence supporting/refuting hypothesis

Improving Reliability

  • Repeat investigation

  • Larger sample size

  • Random sampling

  • Multiple readings for average effect

  • Results confirm/refute the hypothesis