The document discusses different types of variables in experiments including independent, dependent, and extraneous variables. It also describes different scales of measurement for variables like nominal, ordinal, interval, and ratio scales. The document then provides an example experiment where varying concentrations of bromelain extract from pineapple were used to treat acute lymphoblastic leukemia cells over 24 hours and cytotoxic effects were measured using trypan blue staining.

1. Types of variables

2. Variables Can assume only one value Measurable factor that can take any value while under observation/study Constants

4. Types of variables Based on cause and effect Independent/ manipulated (IV) “ cause” Dependent/ responding (DV) “ effect”/”observed” Extraneous/ constant (EV) other variables kept constant

5. Types of variables Based on the value of the variable Continuous with fractional /decimal values Discontinuous/ discrete whole number values, no fractions

6. Types of variables Based on the scale of measurements Nominal qualitative description, name Ordinal/ranking order or sequence mutually-exclusive classes Interval arbitrary zero point Ratio true zero point

7. Pineapple ( Ananas comosus ) contains bromelain extract, an aqueous protease enzyme that has been found to have anti-metastatic activity, low toxicology and have no side effects. Crude extracts were obtained from from a 1:1 ratio of distilled deionized water and filtered pineapple juice precipitated with saturated ammonium sulfate . Varying concentrations at 0%, 1%, 10%, and 100% of distilled deionized water and the extract were used to treat live acute lymphoblastic leukemia (ALL) cells cultured in fetal bovine serum for 24 hours . The cytotoxic efficiencies were obtained as indicated by the permeation of blue trypan dye of cell membranes of unviable cells. The 1% extract yielded a higher number of dead cells than total number of cells than the culture media. The 10% extract showed signs of contamination, and the 100% showed cell eruptions and bloated cells.