STAT 2100H - Midterm Review

# STAT 2100H - Midterm Review - Chapter 1-population total...

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Chapter 1 -population – total set of subjects in which we are interested / -sample – subset of pop. for whom we have data -descriptive statistics – methods for summarizing data (graphs, avgs, percentages, etc.) -inferential statistics – methods of making decisions / predictions about a population based on sample data. -design – planning how to obtain data / -probability – helps to determine chances of an occurrence -random sampling – good and crucial for experiments and studies -subjects – entities that are measured in a study -parameter – numerical summary of a population / -statistic – numerical summary of sample taken from a pop. Chapter 2 -variable – any characteristic that is recorded for subjects in a study -categorical variable – observation that belongs to one of a set of categories (college major, dating status, etc.) -quantitative variable – observation that takes on numerical value that represents magnitude of value (GPA, etc.) -discrete quantitative variable – a count; finite number of possible values (“the number of. ..”) -continuous “ “ - form an interval; continuum of infinitely many possible values (time, height, dist., etc.) -frequency table – shows # of observations/values for variable; counts -percentage table – shows proportions x 100 (percentages and proportions are relative frequencies) -categorical variable graphs – pie charts, bar graphs (Pareto chart – bar graph ordered by highest to lowest freq., Pareto principle – a small subset of categories often contains most of the observations). -quantitative variable graphs -dot plot -stem-and-leaf plot -histogram -dot & s-&-l plots good for small data sets; histograms good for large data sets -histograms more flexible in defining intervals than s-&-l plots -data values retained in s-&-l and dot plots but not histograms -bar chart – for categorical variables, histogram – for quantitative variables - - shape – symmetric -skewed to the right if or skewed if right tail > left tail (highest pt (pop. is -vice-versa - mode) polarized) -time series – data set collected over time; graphically displayed by time plot; common pattern – trend -measures of center – mean and median -mean = sum of observations / number of observations; median – midpt. of obs. ordered from least to greatest -mean = -symmetric shape: mean = median, right skewed: mean > median, left skewed: mean < median -outliers – observations that fall well above/below overall bulk of data -mean can be highly influenced by outliers / median is resistant to outliers / mode – value that occurs most freq. -numerical summary of observations is resistant if outliers have little to no effect on its value -measures of spread – range and standard deviation -range: difference b/w largest and smallest observations -deviation: difference b/w observation and mean (x-x); positive deviation + negative deviation = 0 -variance: avg of squared deviations / -standard deviation: square root of variance -standard deviation =

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STAT 2100H - Midterm Review - Chapter 1-population total...

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