maths

• what is positive correlation?


  As one co-variable increases so does the other
• what is negative correlation?


  As one covariable increases the other decreases
• what is no correlation?


  No relationship between variables
• what are the features of a histogram?


  -all bars same width

  -Gap between bars

  -Categorical data
• what bar chart?


  -No frequency density

  -All bars the same width

  -No gaps between bars

  -Continuous data that keeps on going

  -unshaded bars
• what is the strong negative coefficient?

  minus one
• what is a negative coefficient?


  -0.5
• what is a positive coefficient?


  +0.5
• what is a positive coefficient?


  +0.5
• what is a strong positive coefficient?


  +1
• what is a strong positive coefficient?


  +1
• what are the features of a scattergram?


  -x marks space

  -labels on x and y axis - units

  -no line of best fit

  -title
• what is mean?


  The sum of all the values divided by the number of values
• what are strengths of the mean?


  Valid because it includes all values in its calculations so all is representative
• what are the weaknesses of the mean?


  Is affected by outliers ( skewed)
• what is the mode?


  The most frequently occurring value
• what does bimodal mean?

  Two modes
• what are the strengths of the mode?


  Easiest to calculate

  Best for categorical data
• what are the weaknesses of the mode?

  Less helpful if no mode or there is multiple modes
• what is the median?


  The middle and organised in size order
• what are the strength of the median?


  Not affected by outliers
• what are the weaknesses of the median?


  Less valid because it doesn’t include over values in its calculation

  Unsuitable for larf data sets
• what are the weaknesses of the median?


  Less valid because it doesn’t include all the values in its calculation

  Unsuitable for large data sets
• what is the range?


  The highest value - lowest value
• what does a large range show?


  A lack of consistency
• what does a small range show?

  Consistent
• What are measures of central tendency?


  Mean, mode, median, range, standard deviation
• what is standard deviation?


  A measure of the variability of a set of scores from the main
• what does the largest standard deviation show?


  A largest spread of scores in so less consistent data
• what does a small standard deviation show?


  A smallest spread of scores more consistent data
• what are the positives of using range?


  Quick and easy to calculate
• what are the negatives of using range?


  -Can be distorted by extreme values

  -Doesn’t include all values in its calculation (less valid)

  -Doesn’t show where the data is clustered around the meaning spread out from the mean
• What are the positives of using standard deviation?


  -More valid measure because all of the values are included in its calculation

  -It allows the interpretation of individual scores

  -Less sensitive because all values are included in the calculation
• what are the negatives of using standard deviation?


  -Complicated to calculate

  -Less meaningful of the data is not normally distributed
• what type of curve is normal distribution?


  A bell curve
• what is a skew?


  The long tail in distribution
• what does negative skew look like?


  Asymmetric tail to the left.

  
• what does positive skew look like?


  Asymmetric tail to the left

  
• what is the order on negative skew?


  Mean median mode
• what is the order on positive skew?


  Mode median mean