1. Bivariate Data AS 90425 Complete a statistical investigation involving bi-variate data.

2. Scatter Plots The scatter plot is the basic tool used to investigate relationships between two quantitative variables. Types of Variables Quantitative (measurements/ counts) Qualitative (groups)

3. What do I see in these scatter plots? There appears to be a linear trend. There appears to be moderate constant scatter about the trend line. Negative Association. No outliers or groupings visible. 4540 35 20 19 18 17 16 15 14 Latitude (°S) Mean January Air Temperatures for 30 New Zealand Locations Temperature (°C)

4. What do I see in these scatter plots? There appears to be a non-linear trend. There appears to be non-constant scatter about the trend line. Positive Association. One possible outlier (Large GDP, low % Internet Users). Internet Users (%) % of population who are Internet Users vs GDP per capita for 202 Countries

5. What do I see in these scatter plots? Two non-linear trends (Male and Female). Very little scatter about the trend lines Negative association until about 1970, then a positive association. Gap in the data collection (Second World War).

6. What do I look for in scatter plots? Trend Do you see a linear trend… straight line OR a non-linear trend?

7. What do I look for in scatter plots? Trend Do you see a linear trend… straight line OR a non-linear trend?

8. What do I look for in scatter plots? Trend Do you see a positive association… as one variable gets bigger, so does the other OR a negative association? as one variable gets bigger, the other gets smaller

9. What do I look for in scatter plots? Trend Do you see a positive association… as one variable gets bigger, so does the other OR a negative association? as one variable gets bigger, the other gets smaller

10. What do I look for in scatter plots? Scatter Do you see a strong relationship… little scatter OR a weak relationship? lots of scatter

11. What do I look for in scatter plots? Scatter Do you see a strong relationship… little scatter OR a weak relationship? lots of scatter

12. What do I look for in scatter plots? Scatter Do you see constant scatter… roughly the same amount of scatter as you look across the plot or non-constant scatter? the scatter looks like a “fan” or “funnel”

13. What do I look for in scatter plots? Scatter Do you see constant scatter… roughly the same amount of scatter as you look across the plot or non-constant scatter? the scatter looks like a “fan” or “funnel”

14. What do I look for in scatter plots? Anything unusual Do you see any outliers? unusually far from the trend any groupings?

15. What do I look for in scatter plots? Anything unusual Do you see any outliers? unusually far from the trend any groupings?

16. Rank these relationships from weakest (1) to strongest (4):

17. 2 1 4 3

18. Rank these relationships from weakest (1) to strongest (4): How did make your decisions? The less scatter there is about the trend line, the stronger the relationship is.

19. Describing scatterplots Trend – linear or non linear Trend – positive or negative Scatter – strong or weak Scatter – constant or non constant Anything unusual – outliers or groupings