Stats Notes

methods of organizing, summarizing, and presenting data in informative way. Not estimating future populatio etc but only to summarize pst (i.e. canadian population over years)

methods used to estimate a property of a population using asample

Best guess of a population value based on a sample informationimpossible to test all of the population, so representative sample chosen

identifies categories or attributes. Eg. colour, gender etc.

has numerical attributes. It indicates how much or how many.

can only assume certain values, and there are gaps between variables.(number of bedrooms)

assume any variable within a specific range. (tire pressure)

observations of a qualitative variable can only beclassified and counted. There is no particular order to the labels. (colour of M&M’s, gender)

data are that data classifications are represented by sets oflabels that have relative values and can be ranked or ordered. Distance between valuesnon necessarily equal.

responses classify, indicate order, and the distances betweenconsecutive numbers are meaningful.Data are always numericalZero is a point on a scale – not necessarily the absence of a phenomenon or bottomof the scale

Interval data + absolute zero and the ratio of two number is meaningfulIn this case an absolute zero means the zero value represents the absence of thecharacteristic being studied.

methods used to estimate a property of a population using a sample.

a grouping of qualitative data into mutually exclusive classes showing thenumber of observations in each class.

indicate the fraction of observations in each category (class)

is the decimal expression of the relative frequency, forall observations

a grouping of data into mutually exclusive classes showing the numberof observations in each class.1. Decide on the number of classes. 2 to the k rule. 2^k>n (k classes, n observations), e.g.2^k>40, k>ln(40)/ln(2), k>5.322, set k=62. Determine the class interval or width. �≥�−�/� where i=interval, H=max, L=min3. Set the individual class limits. Avoid overlapping or unclear class limits 1<=Rate<34. Tally the list prices into the classes.5. Count the number of items in each class. The number of observations in each class iscalled the class frequency.

Like a bar chart, but used for quantitative dataHorizontal axis is continuous if data continuousBars are adjacentClass frequencies on vertical axis, class limits OR class midpoints on horizontal axis.

also shows the shape of a distribution and is similar to a histogram. Itconsists of line segments connecting the points formed by the intersections of the classmidpoints and the class frequencies.