Help with Stats questions?
Could anyone help me with this statistics questions? The questions is asking me:
"A research question of interest is whether, in the target population,
there is a dependence between cell phone usage in a course and final course grade. Provide a graphical display using the data above
that addresses the research question."
https://gyazo.com/f11421012ab9e91d1612a7ec5483a278
How would I approach graphing this? I've tried plotting all the points but when I look at my graph it just doesn't make any sense in my head. Especially since the next question is asking me "What can you conclude about the research question based on your graphical display?"
October 20, 2015
7 Comments • Newest first
@juxos: Numbers were used to display the mark percentage.
@sezbeth: got it, thank you so much! really appreciated.
@caca: Alright, the numbers are in correct placing. The only correction I would make for the graph is to rename the y-axis "number of students" rather than "grade"; the color of the lines are indicating the specific grades while the y-axis would be associated with the number of students who received said specific grade. Of course, that may have been my fault due to my initial post (I was assuming you weren't working with colors, which actually helps tremendously with this type of data set).
You are correct in observing a negative correlation, so there's the answer to the second question.
That said, don't dwell too much on the difficulty interpreting the graphical representation. It's just something you gain comfort with over practice, much like anything else involving mathematics, statistics, and so on.
@sezbeth: I tried a line graph and here's what I got. https://gyazo.com/3f04052eb02175fb77fc94714a8961a3 I tried switching it around the first time as you said, with the x-axis as frequency and y-axis as grades but the results were hard to comprehend.. so I tried the x/y axis and the link I've posted above makes more sense. I hope this seems correct.
And would I conclude that there seems to be negative correlation? Since the line graph heads downwards the more times you use a phone.
And I'm taking the first level of Statistics at my school; Elementary Statistics.
@juxos: The problem with a bar graph with this particular question would primarily be that you would have difficulty representing some sort of relation between the two variables. Bar graphs are typically used when focusing on general quantities rather than relationships (though you could get around it by organizing the columns in a greater-to-lesser order or vice-versa).
That said, you can simply re-code the grades as 1,2,3,4 for each respective letter (e.g. 1=D, 2=C, 3=B, 4=A; sort of like the GPA scale without decimals). I probably should've mentioned that in the first post for the y-axis. I must've overlooked it.
@sezbeth: you cant do grades by 10 because its only given as a letter grade. I might be wrong though.
OT: You can try something like a quad bar graph
Frequency of phone use as x-axis (denoted as 0,1,2,3,4,5, etc.) and grades as y-axis (denoted as 0,10,20,30,etc.) on a line graph.
The point of this question is to establish whether there's a correlation between phone use and final course grades. Once you finish the graph, state whether you observe a negative correlation, positive correlation, or no correlation.
You can't just take the data at face value and try to graph it like that. Part of statistics is learning to develop an intuition for how data sets should be graphically organized, as well as developing a sense of what relationships may be present between two (or more) variables.
Edit: Also, if I may ask, what statistics course are you taking?