Flashcards on Graph Plotting and Data Analysis
Graph Plotting & Data Analysis: A Student's Guide to Understanding
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Graphing continuous data
10 cards
Card 1
Question: When both variables are continuous, what type of display should you use and why?
Answer: Use a graph because both variables are numerical and can take any value within a range, so a graph best shows their relationship.
Card 2
Question: How should you mark individual data points on graph paper?
Answer: Use a sharp pencil and draw neat little crosses for each point (do not use blobs).
Card 3
Question: If asked to draw a line or curve of best fit, how should you draw it?
Answer: Draw a line through or as near to as many points as possible, ignore anomalous results, do not join the crosses, and make the line big (cover at least
Card 4
Question: What information does the gradient (slope) of a graph give you?
Answer: It tells how quickly the dependent variable changes as the independent variable changes (rate = change in y divided by change in x).
Card 5
Question: How do you calculate the gradient of a straight-line graph from two points?
Answer: Pick two easy-to-read points far apart, compute change in y and change in x, then gradient = (change in y)/(change in x). Units = (units of y)/(units
Card 6
Question: Using the example points (1.6 s, 2.0 cm^3) and (5.2 s, 6.8 cm^3), what is the gradient and its units?
Answer: Change in y = 4.8 cm^3; change in x = 3.6 s; gradient = 4.8/3.6 = 1.3 cm^3/s (or cm^3 s^-1).
Card 7
Question: How do you find the gradient of a curve at a specific point?
Answer: Draw a tangent to the curve at that point and find the gradient of the tangent line.
Card 8
Question: What is an intercept on a graph?
Answer: The intercept is where the line of best fit crosses an axis: the x-intercept crosses the x-axis and the y-intercept crosses the y-axis.
Card 9
Question: What are the three types of correlation between variables shown on graphs?
Answer: Positive correlation (both increase together), inverse/negative correlation (one increases while the other decreases), and no correlation (no relation
Card 10
Question: Does correlation on a graph prove causation?
Answer: No — correlation does not mean one variable causes the change in the other; other factors may be involved.