PSYC 301 1st Edition Lecture 1DESCRIBING DATABranches of Statistics1) Descriptive statistics – describes or summarizes a group of numbers2) Inferential statistics – makes inferences that go beyond numbersOutline of Current Lecture i. Different types of Variablesii. Presenting data in graphsiii. Distributing dataCurrent Lecturei. Different types of variables- Relevant variables:o Independent variables / IV / predictor variables (what you manipulate)o Dependent variables / DV / outcome variable (what you’re measuring)- Values:o All variables can take on different values (gender, memory span, etc.)o A persons value on a variable is called a score- Score:o One individuals value/scoreKinds of variables:- Nominal: categories, names, gender, species, etc.o Discrete : only certain values are possible (values that are cut and dry)- Ordinal (rank order): relative ranking; variables with values that can be organized.(Year in college, class rank, etc.)- Interval (equal-interval): numbers; age, height, weight, etc.o Continuous: within this range, mostly any valuable is possible.- Ratio: an interval that can include a zeroThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.ii. Presenting data in grapha. Frequency table: a table filled with frequency; how often does each score happen?i.b. Grouped frequency table: how often does each score happen in the groups of the dependent variable i.c. Histogram: displays the frequency of different valuesi.d. Bar Chart: relating the dependent variable to the independent variablei.e. Line Chart:i.f. Scatter plot: each dot is a collection of two different variablesi.Kinds of Chartsg. Histogram – x-axis: DV (continuous), y-axis: frequencyh. Bar Chart – x-axis: IV (discrete), y-axis: DV (continuous)i. Line Chart – x-axis: IV (continuous), y-axis: DV (continuous)j. Scatter Plot – x-axis: IV (continuous), y-axis: DV (continuous)iii. Distributing Data: The first step in all data analysis is finding the shape of the distribution of data.a. Bell-Shaped curve, symmetric b. skewedi. Types: digit span, salary, highway speeds, age you learned to read, etc.c. skewedi. Types: test scores, life span, etc.d. multimodal (2 peaks/2 modes)e. outliersQUESTIONS:- If you collected data on the most popular baby names of last year, what type of variable is this?o Nominal- What are the biggest differences between histograms and bar charts?o A histogram has the frequency on the y-axis and the DV on the x-axis, while the bar chart has the IV on the x-axis and DV on the y-axis- What does it mean when a distribution has multiple modes? Is skewed?o The data collected has more than one score that happened the most
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